Otto v. Koppers Co. (147 F. Supp. 552, 1956)

BOREMAN, District Judge.

This is an action for patent infringement, involving two patents owned by the plaintiff, Dr. Carl Otto (hereinafter sometimes referred to as “Otto”), who is a citizen of the State of New York, an engineer, and the head of Otto Construction Company, a New York firm engaged in the design and erection of by-product coke oven plants. Defendant, Hoppers Company, Inc., a Delaware corporation (hereinafter sometimes referred to as ‘■‘-Khppqrs”)', has principal offices in Pittsbfifgh, Pennsylvania, is licensed to do business in West Virginia, and is also engaged in the design, and erection of by-product coke oven plants. Defendant, Wheeling Steel Corporation, a Delaware corporation (hereinafter sometimes referred to as “Wheeling”), owns and operates a plant at Follansbee, in the Northern District of West Virginia, wheré apparatus and processes charged to infringe both Otto patents, have been built and operated.

The original complaint charged infringement of Otto’s U.S.Patent No. 2,-599,067 which discloses and claims method and apparatus for the production of ammonium sulphate as a by-product from coke oven gas by means of a “spray” type saturator. After answer by' Koppers and Wheeling challenging validity of the claims of the patent and denying infringement, Otto served on Koppers. a- number of interrogatories, to some^ of which Koppers objected. This Court ruled on these objections, requiring answers to some and sustaining objections to others. Based upon information 'thus obtained by Otto through interrogatories, an amended complaint was filed expanding the original complaint to include an additional charge that the defendants had infringed an earlier Otto U.S.Patent No. 2,423,794, which discloses and claims apparatus and process for production of ammonium sulphate as á by-product from coke oven gas by means of a special “flare mouth” type dip pipe saturator. The defendants answered this amended complaint denying infringement of the additional patent as well, asserting that its claims were also invalid, and specifying the particular prior art upon which defendants would rely to sustain their charge of invalidity as to both’ patents.

In considering Koppers’ objections to interrogatories prior to the filing of .Otto’s amended complaint, it became necessary to determine the territorial scope of proof of alleged acts of infringement of Patent No. 2,599,067 and this Court’s decision on that question is reported in Otto v. Koppers Company and Wheeling Steel Corporation, 134 .Fed.Supp. 886. By the effect of said decision, evidence of infringement as to both patents is limited to structures built and processes used by these defendants in the Northern District of West Virginia.

Explanation of the subject matter of the two Otto patents here involved appears to be necessary. The gas produced from the coke manufacturing process contains ammonia in substantial quantities. For certain reasons, it is desirable, or even necessary,' to remove the ammonia from the coke oven gas before the gas can be properly and safely utilized. Over the years, the by-product coke oven industry has faced the problem of removing the ammonia from the gas and at the same time obtaining a byproduct disposable to economic advantage.

The generally accepted solution of this problem has been to bring the coke oven gas containing the ammonia into contact .with a liquor containing sulphuric acid so that a reaction occurs between the ammonia and sulphuric acid, thus producing marketable ammonium sulphate.

For years, most of the by-product ammonium sulphate in this country was produced in saturators in which the gas was bubbled through a bath of liquor containing sulphuric acid. This bath consisted of an acidified saturated solution of ammonium sulphate containing solid crystals of ammonium sulphate, and the effect of the ammonia reacting with the acid was to produce, directly in the bath, more crystalline sulphate. Crystals were periodically withdrawn and acid replaced to enable the process to proceed substantially continuously. Because some solid salt was constantly being deposited on the apparatus itself, it was necessary periodically to “kill” the bath, or to so dilute the bath with water and acid that such deposits would dissolve. The “kill” did not interrupt the removal of ammonia from the gas which continued to flow and the acid-ammonia reaction continued, but under such conditions of dilution that no crystal formation could take place. The pipe through which the gas passed into the liquor in this conventional apparatus was called a “crackerpipe” and usually dipped some twenty-five to thirty-eight inches into the liquor bath. The result was that the gas had to be forced or pumped against a high pressure head in order for it to pass through the cracker-pipe against the seal of the liquor bath.

It seems to be undisputed that the early saturators, known as the cracker-pipe type, were satisfactory when installed, removed a high percentage of the ammonia from the gas and apparently continued to be satisfactory for many years. The true background history appears to be that soon after 1939, the problem of handling more coke oven gas became acute because the steel industry was putting in more coke ovens. The problem which Dr. Otto sought to solve arose soon after he came to this country in 1939 and he stated this problem as follows: “The problem was that it was the trend of the times, by-product plants were getting too small for the gas output * * *. Therefore, it was important to design apparatus which could take care of the conditions to get bigger output through the by-product plants, resulting in remodeling the old by-product plant.” (Trans, page 160).

It was only natural that the producing companies should try to keep the cost of producing ammonium sulphate as low as possible, and it follows that a reduction in the high pressure head would reduce the power cost of pumping the gas through the liquor bath in the saturator.

While both patents in suit relate to ammonia saturators and the incidental ■production of ammonium sulphate crystals, each patent describes and claims different saturator apparatus and different methods of operation. The respective defenses to the charges of infringement of the two patents involve different prior art, different issues of patentability and different issues of infringement. Therefore, each patent, the claim of infringement and the defense thereto will be separately considered.

U. S. Patent No. 2,423,794

(Otto Flare-Mouth)

The application for this patent was-filed on August 25, 1943, and patent was issued on July 8, 1947. The original application contained sixteen claims,- all of which were subsequently canceled. Claim 1 was a broad method claim and Claim 7 was a broad apparatus’ claim. These claims attempted to cover broadly the idea of passing the gas “in a generally horizontal direction” between “an upper wall surface” and the surface of the liquor bath. These broad claims were not limited to a flare-mouth but were drawn to include a form in. which there was no central crackerpipe but a peripheral type of crackerpipe, broad enough to cover any angle of the “upper wall surface” and were not even clearly limited to having this surface slope downwardly.

All of the sixteen original claims were .rejected as being substantially met by a number of prior art references. There followed an extensive interchange between the Patent Office Examiner and Otto’s attorney which resulted in an Official Action of October 29, 1946, in which the Examiner made “final” his rejection of the broad claims, but suggested that he would allow a single claim .which is identical with Claim 1 of this patent, as hereinafter set forth.,

The allowance of this claim was preceded by several interviews ■ between Otto’s attorney and the Examiner, but there is no record in the file,history of the arguments which persuaded the Examiner to allow Claims 1, 2 and ,3, as .contained in the patent. The defendants call attention to Rule 133 of the Rules of Practice of the Patent Office, which requires that “a complete written statement of the reasons presented at the interview warranting a favorable action must be filed by the applicant”.

The plaintiff’s amended . complaint charges that defendant Koppers has, since July 1947 and within six years, infringed Patent No. 2,423,794 by, with.out authority from Otto or his predecessor in title, using coke oven apparatus embodying the patented invention, using methods embracing the patented invention for the continuous production of sulphate of ammonia, and actively inducing others, including Wheeling, to use said apparatus and methods of the patented invention. Said amended complaint charges that the defendant Wheeling, since July 1947 and within six years, infringed said patent by, without authority from Otto or his predecessor in title, using by-product coke oven apparatus embodying the patented invention made for it by Koppers, and using methods embracing the patented invention for the continuous production of sulphate of ammonia.

This patent contains three claims but, from the record, the plaintiff’s arguments and briefs, it' is apparent that plaintiff’s counsel is not relying upon alleged infringement by these defendants of Claim 2, but only Claims 1 and 3 of the patent. These claims are quoted as follows :■

“1. A saturator for producing ammonium sulphate comprising in combination an enclosed tank, an overflow outlet'in the wall of said tank for establishing and maintaining the level of liquor therein, a crackerpipe having a lower vertical portion centrally disposed in said tank and having an outwardly downwardly flared mouth at its lower end, the rim of said flare mouth being at a level Islightly below the overflow level and the flared portion having a downward slope from the crackerpipe toward the rim of from 4° to 15° to the'horizontal.”

“3. In a process for producing ammonium sulfate which comprises passing ammonia-containing gas into contact with a bath liquor containing sulfuric acid, the improvement which consists in passing the gas beneath a surface which slopes downwardly, from the point at which it is brought in, at an angle of 4° to 15° to the horizontal, the lower edge of said surface being below the normal liquid level, so that the liquid surface beneath the sloping surface is depressed and agitated by said gas, the rate of gas flow being in excess of two cubic feet per second per inch of length of the discharge edge of said surface.”

This patent, which has been referred to as the “flare-mouth” and at the trial and in the briefs referred to as the “bell-mouth”, discloses three different forms of apparatus, the first in Figures 1 to 6, the second in Figures 9 and 10, and the third in Figures 11 and 12. The patent goes into great detail in describing these three forms, and devotes much space to the explanation of features admitted to be old, such as the flushing of the walls of the saturator and the recirculation of the liquor in the crystallizing chamber at the bottom of the saturator. But the patent itself admits that almost everything shown is old, and that the only novelty claimed relates to the “form and disposition of the means for passing the incoming gas into scrubbing contact with the bath liquor”. In other words, the only claim to novelty relates to the flare-mouth at the lower end of the crackerpipe.

In describing how he came to make the invention disclosed in this patent, plaintiff Otto said in his testimony at the trial that “the old-type crackerpipe saturator made the gas bubble through the liquor in a vertical direction” and that he wanted “to go over from the vertical flow to the horizontal flow”. He stated: “My purpose was really to make it flow horizontally and contact the liquor”.

The original file wrapper discloses amendment after amendment presented by the plaintiff, Dr. Otto, through his attorney, after the Examiner had criticized the application and indicated a rejection of all claims. The final suggestion of the Examiner of the allowance of one claim was adopted, which suggested claim was carried into the patent as Claim 1.

An examination of the file wrapper discloses that a desperate effort was made by plaintiff’s attorney to add to the original specifications, by providing that the submerged lower peripheral edge of the outwardly flared discharge mouth should have a radial extent not less than 65% of the radial extent of the tank, in substantially all directions from the tank axis. It was argued by plaintiff’s attorney that “the advantage is believed by the applicant to be due to the damping effect on the bath liquor surging movement of the resistance to flow through the relatively small angular space between the mouth piece discharge edge and the tank wall through which the bath liquor must move up and down as surging occurs. The newly directed claim 18 is directed to the feature just referred to. None of the references disclose anything of the sort. The difference in mouthpiece lip and tank diameters specified in new claim 18, marks no mere change in degree from the prior art. The dimensions specified in claim 18 insure an effective damping opposition to surging movement of the bath liquor, and no such damping action is obtainable with apparatus constructed in accordance with the regular practice of the prior art, because of the much smaller crackerpipe mouthpiece diameter relative to tank diameter”. As shown before, the Examiner disallowed this new claim, as well as all other original claims.

Figure 8 of the patent is a graph which purports to represent the “degree of incline” in relation to the “gas flow in cubic feet per min.”, showing the “line of light ripples”, the “line of strong ripples”, and the “line of surge”. The original application stated: “While it is essential to the full attainment of the advantages of the invention that the direction of gas flow through the free gas space of the scrubbing zone should be approximately horizontal, I have found it practically desirable to incline the vgall surface forming the roof of said gas space at a small angle to the horizontal with the lower edge of said wall surface at the gas discharge edge of said space. Said angle which may vary from a minimum of four or five degrees to a maximum not greater than fifteen degrees. Unless the wall forming the roof of the free gas space is so inclined, gas flow conditions and bath liquor surging actions may occur which will materially interfere with the efficiency of the scrubbing action, and which tend to cause objectionable deposits of sulphate of ammonia crystal or ‘salt’ on said wall.” In the original application, Figure 8 is described as “a chart illustrating test apparatus results obtained with different rates of gas flow and with different roof in'clinations”.

At the bottom of page 18 and following on page 14 of the specifications as contained in the original application, we find the following: “As a result of studies and tests made by me, I believe that the under surface of the mouthpiece lip * * * or analogous gas space roof or top wall should incline downwardly toward the discharge end of the gas space generally' * * *. As stated above, the inclination to the horizontal of the under surface of the lip portion shown in the drawings is thirteen degrees. I believe that angle may be increased to about fifteen degrees and may be decreased to about four or five degrees without any radical effect on the general operation of the saturator. However, with the above mentioned mouthpiece dimensions, I now believe that an increase in the angle above thirteen degrees would be disadvantageous because it would reduce the velocity of the gas in the portion of the gas space adjacent the inner edge of the lip portion * * * so as to significantly reduce the above mentioned rippling and atomized actions adjacent the center of the surface B2. I now believe also that an angle smaller than four or five degrees is conducive to a bath liquor surging action which will subject the tank structure to objectionable mechanical stresses and which produces a sort of pulsating gas outflow beneath any particular small portion of the corner edge D6. Such flow pulsations reduce the efficiency of the scrubbing action and are conducive to objectionable salt deposits on the under side of the mouthpiece lip.”

The communication of the Examiner to the plaintiff’s attorney of October 29, 1946, is in part as follows: “As stated on page 14 of the specification, the limiting range • of 4 to 15 degrees for the angle of the cracker pipe mouth flare to the horizontal is based upon conjecture. It appears from Figure 10 and the discussion thereof that this may not be the case and that the limits might actually be based on experimental evidence. However, the disclosure should be so worded as to state the limits positively rather than as a prophetic statement of belief. It is not clear what Figure 8 is intended to show. The curves appear at best not to represent any important operative control, but they also seem inaccurate in that any increase in pressure head would cause an increase in gas velocity. It does not. appear that these two factors can be independently varied. Since the figure adds nothing to the case it might be cancelled; if it cannot be more adequately explained. The claims are rejected as based upon an indefinite disclosure. The new figure of 65% of the radial extent of the tank being taken up by the flared discharge pipe is new matter and the insertion directed on page 20 by the amendment filed June 25, 1946, is required to be cancelled. A careful consideration of the claims indicates that they are indefinite in that, on reading them, one gets the impression that the slope of the flare is upward from the pipe rather than down. The following claim, considered allowable, is suggested as representing the inventive concept in acceptable form:”. Then follows the suggested form of claim, which is the same as claim 1 of the patent. The plaintiff’s attorney, on November 25, 1946, and in response to the office action of October 29, 1946, amended the application and cancelled all claims except claims 1, 2 and 3 of the patent, which were subsequently allowed.

The original file wrapper shows certain patent references of record in the file:

U. S. patent Sperr, 1,986,900, January 8, 1935; U. S. patent French, 2,123,887, July 19, 1938; U. S. patent Pennock et al., 1,012,273, December 19, 1911; Great Britain, 361,935, November 23, 1931; German Still, 648,540, August 3, 1937; German Koppers, 272,601, April 4, 1914; German Still, 657,439, July 19, 1936.

Plaintiff’s attorney, on June 29, 1944, amended the application and, in the typewritten remarks accompanying the amendment, referred to other prior art patents, namely:

U. S. patent Marquard, 1,589,809, June 22, 1926; U. S. patent Mueller, 1,936,308, November 21, 1933; U. S. patent Underwood, 2,002,557, May 28, 1935.

That Otto, at the time of filing his application, considered the matter of horizontal gas flow to be the heart of his invention is shown by the fact that it is the important feature stressed in the sixteen original claims. All of them include this feature. Some, such as claim 1 and claim 7, claim it very broadly. Others claim it in combination with other features. But the Patent Office refused to recognize these claims as defining invention and allowed very limited claims, as shown in claims 1, 2 and 3 of the patent.

The defendants have cited other patents and publications prior to the alleged invention of Otto and more than one year prior to Otto’s application for his patent, namely:

U. S. patent Sperr, 1,928,509, September 26, 1933; U. S. patent Ogden, 2,-226,101, December 24, 1940; German patent Wagener, 216,069, February 19, 1909; Thau article, Publication Oel Kohle, pages 307-309, May 1, 1941.

The defendants rely on these cited patents and also on Still 648,540 and Koppers 272,601 in urging invalidity of Otto patent No. 2,423,794 because of prior disclosure of Otto’s claimed invention and every material and substantial part thereof. Copies of 'all prior art patents and the Thau article are to be found in Defendants’ Exhibit 18. Referring to patents to Koppers, Ogden, Sperr, Still and Wagener and to the Thau article, it would appear that each of these items of prior art discloses a saturator having a bell mouth, and it would further appear that the object of the bell-mouth is to spread the gas horizontally. The angles of these bell-mouths vary from the relatively steep angles of Koppers and Figure 19 (page 309) of the Thau article, to the flatter angles of Ogden, Sperr, Still and Figure 16 (page 308) of the Thau article.

One of the most significant patents is that to Wagener. This patent was explained in detail by the witness Helm, an expert for the defendants (Trans., pages 437-440), and his explanation appears to support his conclusion that the only difference between Wagener and plaintiff Otto is that in Wagener the flared portion of the crackerpipe has a slight upward inclination. Wagener says that, in his saturator, “the gas is spread out in a flat layer upon the top of the bath and is brought into the most intimate possible contact with the latter”. Of the prior art references applied by the defendants against plaintiff Otto, only Koppers and Still were cited by the Patent Office.

From the prior art, the Court concludes that the horizontal flow of gas into the mother liquor bath was well known for some time prior to the filing of the Otto application. If that is true, wherein does Otto’s claim to invention in his flare-mouth patent lie? Is it invention (1) because the bell-mouth slopes downwardly to horizontal at an angle specifically limited to the range of 4° to 15°; or (2) because the bottom of the bell-mouth is located “slightly below” the overflow level of the liquor bath; or (3) because the patent specifies a rate of gas flow in excess of two cubic feet per second per inch of length of the discharge edge of the downwardly sloping surface ?

Consideration will first be given to question (1) above. As has been shown, the Patent Office required the adoption of a specific range of angles, or a downward slope of from four degrees to fifteen degrees to the horizontal. However, nothing was produced, either before the Patent Office or at the trial of this case, to show that this range is critical. The graph or chart, Figure 8, of the patent contains no evidence that there was anything critical in this range of angles. In fact, the Examiner stated in the office action of August 25, 1943, “It is not clear what Figure 8 is intended to show;” also, “the limiting range * * * for the angle of the crackerpipe mouth flare to the horizontal is based upon conjecture”. Otto himself admitted that Figure 8 does not show that the four degree to fifteen degree range is critical. In response to questioning by his attorney at the trial (transcript page 287), Otto stated: “It is right what I said yesterday, that I accepted the limits of the Patent Office to limit the patent to the claim between the critical points four and fifteen degrees. But I agree that that is not definitely shown on this graph. Today looking at this graph, I should say you could say that the limit is between one and ten degrees, etc.”. It was contended by Otto that line 9 as shown on Figure 8 can be extended by “extrapolation”, but such extension can be based solely on the theory that the line would continue indefinitely at the same angle it had before it left the graph. Such “extrapolation” would preclude any abrupt change of angle where it would cross the vertical line representing a fifteen degree angle. Otto admitted that there was no abrupt change in either of the lines 9 and 10 at four degrees or at fifteen degrees, but I am unable to find any abrupt change at one degree and ten degrees as Otto stated. Actually, the only abrupt change shown on the graph is in line 10 at 7.15 degrees, but no reference has been made at any time to this change, and evidently it is not abrupt enough to be critical.

At the most, the graph, Figure 8, merely shows that under certain conditions in a small model saturator containing water, the observer saw ripples. There is no proof that such ripples are present in a commercial saturator, or that they would contribute in any substantial degree to increasing the gas-liquid contact if they were present. Nor is there any proof that conditions observed in a small model containing water would hold true for a commercial saturator containing “mother liquor”, which has a much higher density than water, and contains ammonium sulphate crystals therein. The exact angle of the bell-mouth appeared, at the time of the filing of the patent application, to be a matter of minor consequence. The original specification stated that it was “practically desirable” to incline the wall of the bell-mouth at a small angle to the horizontal, and in several passages mentioned a minimum angle of four or five degrees; that the inclination to the horizontal of the under surface of the lip portion of the mouthpiece shown' in the drawings is thirteen degrees; that Otto believes the angle may be increased to about fifteen degrees and may be decreased to about four or five degrees without any radical effect on the general operation of the saturator; that an angle smaller than four or five degrees is conducive to a bath liquor surging action producing a sort of pulsating gas outflow, with a corresponding reduction of the efficiency of the scrubbing action.

Again, attention is directed to the proposal, disallowed by the Examiner, that the lower peripheral edge of flared discharge mouth should have “a radial extent of not less than 65 % of the radial extent of the tank” to insure an effective damping opposition to surging movement of the bath liquor. There is nothing in the patent to indicate that 4° is a sharp division point, with no surging above 4° and with surging below 4°. In fact, the graph, Fig. 8, as explained in the specification (Col. 9, lines 3-8), shows that in the tests surging action occurred only at high rates of air flow and then only at angles between 0° and 1°. Otto confirmed this in his testimony (Trans., page 288).

On page 27 of the plaintiff’s main brief appears this heading: “The Numerical Limitations in the Claims Are Not To Be Construed as Critical”. Under this heading, beginning at the bottom of page 27, plaintiff’s brief states: “From an examination of the file history of the patent (PX3), it is apparent that the Examiner in effect picked the 4° and 15° limits which Dr. Otto asserts are not critical in the sense that they define the precise limits of his invention.” * * * “Dr. Otto further stated he did not know if one making a crackerpipe with, a three-degree flare would infringe his patent or not since he did not know American patent law or the range of equivalents that could be applied to elements of his claims * * *. He felt that primarily his invention was defined in the ■ graph from which one could determine for different installations the correct degrees of inclination. * * * It is seen, by reference to the original application as filed, that Dr. Otto did not state positively that the angles were critical, nor were they ever so represented to the Examiner and should not be so considered now.”" Therefore, it appears that counsel for the plaintiff and counsel for the defendants agree that there is nothing critical in the 4° to 15° limits.

Consideration will next be given to question (2). Claim 1 of the patent describes the rim of the flare-mouth as. being “at a level slightly below the overflow level”. Claim 3 refers to passing the gas beneath a surface which slopes, downwardly, “the lower edge of said surface being below the normal liquid level”.

There was no indication in the Otto, application as originally filed that there was anything critical in any particular-depth of submersion of the flare-mouth-None of the claims contained any statements relative to this depth of submersion until a claim was suggested by the Examiner in his action mailed October 29, 1946, and which was adopted by Otto, in his amendment and finally Claim 1. There is nothing to be found, either in the patent or in the file history, concerning any advantage flowing from having the flare-mouth at any particular depth of submersion. Nor was any such evidence produced at the trial. In the absence of any showing of advantage, the inclusion in Claim 1 of the statement, that the flare-mouth is located “slightly below” the surface does not help to differentiate from the prior art patents. The evidence disclosed only three actual installations by Otto of the flare-mouth saturator. Each of these installations shows a different depth of submersion of the flare-mouth. In one installation, the flare-mouth was 8 inches below the minimum overflow level and 19 inches below the maximum overflow level. In another installation, the flare-mouth was 6 inches below the “bath liquor level”. At a third installation, the flare-mouth was 2 inches below the minimum overflow level and 4 inches below the line marked “liquor level”, which is presumably the normal level of the bath. In these actual Otto installations, the depth of immersion of the flare-mouth varied from a minimum of 2 inches to a maximum of 19 inches. No evidence was introduced to explain these differences or to show that any particular depth of immersion was critical.

Question (3) will next be considered. Claim 3 calls for a rate of gas flow “in excess of two cubic feet per second per inch of length of the discharge edge of said surface”. The only advantage recited in the patent for this rate of gas flow is that it causes liquor to splash up onto the walls of the saturator and “In consequence, a down-moving film of bath liquor is maintained on the gas space wall which carries with it its sulphate crystal content of said film”. (Patent, col. 12, lines 7-43). But Otto himself testified that this is done in every crackerpipe saturator and stated: “I do not think that this patent in suit has more entrainment or works in this respect different from the old-type eraekerpipes”.

Moreover, any claim for advantages resulting from a gas flow “in excess of two cubic feet per second per inch” is not supported by the graph' shown on Figure 8. At the left of the graph is shown “gas flow in cubic feet per min.” through a space having a “horizontal width of one inch”. (Col. 8, line 75). The highest figure for gas flow is the top figure “50”, which means 50 cubic feet per minute per inch of horizontal width. The rate specified in Claim 3 is two cubic feet per second and it follows that that rate multiplied by sixty would yield the rate per minute, or 120 cubic feet. This rate of 120 cubic feet per minute is more than twice the top rate of 50 shown on the graph. In other words, this rate is away above the graph, and there is no showing on Figure 8 that any specially advantageous results are obtained with angles of 4° to 15° and at the rate of 120 cubic feet per minute, nor is there any testimony in this case as to such results. It appears that this case contains no proof that a rate of gas flow as called for in Claim 3 is critical.

One of the references cited by the Examiner against the Otto flare-mouth application was the German patent to Still No. 648,540 (copy in defendants’ Exhibit 18). In arguing against this patent, Otto’s attorney said that it did not have an open bell-mouth, but that there is a solid bottom across the bell-mouth (file history, page 51, 'last paragraph). At the trial of this case, the defendants’ witness Helm stated that, in his opinion, the drawing of the Still patent shows an open bell-mouth and that the “extra line at the extreme bottom of the bell-mouth represents ribs”. (Trans., page 443). Helm stated that this was also shown in Figure 2 of the Still patent.

Plaintiff’s attorney criticizes Helm’s testimony and asserts that on cross-examination Helm “stated that he was mistaken”. However, what Helm actually said was that he was mistaken about Figure 2, since Figure 2 is a section taken at a different point from that which he had in mind when he first testified. But he reiterated that the Still bell-mouth is open and has ribs. The actual statement by Helm on cross-examination was, “That is correct. I was wrong in saying Fig. 2 shows anything about the bottom of the bell-mouth, but that does not change my conclusion in any way that the bell-mouth crackerpipe is open at the bottom and provided with ribs”. (Trans., page 586). Actually, the Still patent shows a bell-mouth, called a “Distribution Ring 4”, which spreads the gas out horizontally. The bell-mouth shown in this Still patent is at a. flat angle, not specified, but presumably less than the 4° angle’ mentioned by Otto. There is no evidence in the record to contradict this testimony of the witness Helm, and it would appear that the record establishes this Still patent as a very pertinent reference.

Another reference cited by the Examiner was the German patent to Hoppers No. 272,601. (copy in defendants’ Exhibit 18). The witness Helm stated that this patent shows a saturator with a bell-mouth which performs the same functions as the Wheeling saturator is claimed to infringe. (Trans., page 441). Obviously, the purpose of using the flare-mouth crackerpipe is to spread the gas more widely through the liquor bath. In arguing against this Hoppers patent, the only distinction Otto’s attorney was able to point out was the difference in angle of the bell-mouth. (Trans., page 51). But, as hereinbefore indicated, no showing was made by Otto that there is anything critical in the 15° angle and this is, therefore, a mere difference in “degree”. It appears to this Court that the Examiner was misled into believing that there was some invention in this Otto patent. He decided to allow Otto a very limited claim, so he suggested to Otto a claim into which he gathered all the “differences” he believed were present in the Otto disclosure, insisting, however, upon the 4° to 15° angles. There is no proof in this case of critical significance in the “differences”.

It is well settled that a mere aggregation of old elements which, in the aggregation, perform no new or different function from that previously performed is not patentable invention. Lincoln Engineering Co. of Illinois v. Stewart-Warner Corp., 303 U.S. 545, 549, 58 S.Ct. 662, 82 L.Ed. 1008; Anderson Co. v. Lion Products Co., 1 Cir., 127 F.2d 454, 457; Mabey v.. Howard & Lewis Motor Sales, 1 Cir., 132 F.2d 40, 41. “An assembly of old elements taken from prior arts does not involve exercise of inventive faculty, even though assembly is beneficial and results in a successful improvement.” Davis v. Buck-Jackson Corporation, D.C., 138 F.Supp. 908, affirmed 4 Cir., 230 F.2d 655, 658, certiorari denied 351 U.S. 950, 76 S.Ct. 846. In affirming the decision of the District Court, the Fourth Circuit Court of Appeals stated: “ ‘It is the conclusion of this Court that the Davis patent represents an assembly of old elements taken from prior arts relating to allied types of construction and, while undoubtedly a beneficial and successful improvement, does not involve the exercise of inventive faculty; thus the patent is invalid. Interstate Rubber Products Corp. v. Radiator Specialty Co., Inc., 4 Cir., 214 F.2d 546.’ ”

A recent case on “criticality” is Helene Curtis Industries v. Sales Affiliates, D.C., 121 F.Supp. 490, affirmed 2 Cir., 1956, 233 F.2d 148, 155. The law of “criticality” is set forth in the opinion of the District Court. 121 F.Supp. 490. In that case, the court held invalid a patent which covered the use of mercaptan in hair waving, and the claims of the patent contained some numerical limitations. In holding the claims invalid because the numerical limitations in the claims were not in fact critical, the Court of Appeals said: “At most, all these limitations disclosed some teaching — perhaps useful teaching — as to matters of degree affecting the use and selection of mercaptans in hair waving. But such teaching, we hold, did not rise to the level of patentable invention: it did not warrant a private monopoly over the preferred area of the previously disclosed genus of mercaptan hair waving. * * * ‘Thus, as has frequently been said, the mere location of the optimum conditions of use for a known composition of matter does not constitute “invention” so as to entitle the discoverer thereof to a monopoly. That objective, however useful the final result, can be achieved by “patient experiment” [citing cases]; no inventive genius is necessary. Rather, it is only where, other requisites being present, the patentee has found a point or points at which some result differing in kind — and not merely in degree — from the results achieved by the prior art, that an inventive act may be said to exist.’ ”

Plaintiff’s main brief states that Otto did not state positively that the angles were critical, nor were they ever so represented to the Examiner, and should not be so considered now. It was the Examiner who, for some reason not of record, picked the 4° to 15° limits and put them into a claim which he suggested to Otto’s attorney. Whether it was represented to the Examiner that the angles were not critical cannot be determined because the arguments which led to the allowance of the claims were omitted from the file history. It is the opinion of this Court, from an examination of the file history, that the Examiner considered the range 4° to 15° to be critical, else there is no rational explanation of his allowance of the claims of the patent. It seems clear that if the Examiner had been informed that “the numerical limitations in the claims are not to be considered as critical”, he would never have allowed the claims. The Court concludes that the patent is invalid for lack of invention. In view of this conclusion, it would seem unnecessary' to consider the matter of 'infringement. However, that issue will be discussed briefly.

Otto’s broad claims were rejected and withdrawn while the alleged invention was pending in the Patent Office. In view of the evidence at the trial which will be hereinafter mentioned, Otto is, in effect, contending that the narrow and limited claims should be given the same breadth and interpretation as the abandoned claims. If the patent could be found valid at all, it should be strictly construed and alleged acts of infringement must fall within the limited range of the allowed claims. It is not a proper case in which to apply the doctrine of equivalents.

The evidence introduced at the trial disclosed that the installation of the flare-mouth craekerpipe by Koppers at Wheeling had an inclination of 3° from the horizontal. It was not within the range of 4° to 15° specified in Claim 1 of the patent. In addition, the evidence disclosed that the rate of gas flow at the Wheeling installation never, at any time, equalled or exceeded the rate of two cubic feet per second “per inch of length of the discharge edge” of the rim. In normal operation, the throughput of gas in that installation was 1.56 cubic feet per second, although for a short period an abnormal and temporary throughput was at the rate of 1.97 cubic feet per second per inch of the discharge edge of the rim.

Infringement of Claim 2 of the patent, which called for slots, is not seriously urged by the plaintiff, but the evidence disclosed that there were no slots in the Wheeling installation.

If validity of the patent were sustained, for this Court to construe its claims as covering the invention as now asserted by Otto, it would have to give to the patented claims a scope and effect equivalent to claims originally made by Otto, rejected by the Examiner, and cancelled in order to secure allowance of the patent. “ ‘Where a patentee has narrowed his claim, in order to escape rejection, he may not “by resort to the doctrine of equivalents, give to the claim the larger scope which it might have had without the amendments, which amount to disclaimer” ’ ”. Lewis v. Avco Manufacturing Corporation, 7 Cir., 1956, 228 F.2d 919, 924. “ ‘It is a rule of patent construction consistently observed that a claim in a patent as allowed must be read and interpreted with reference to claims that have been cancelled or rejected and the claims allowed cannot by construction be read to cover what was thus eliminated from the patent’ ”. Lewis v. Avco Manufacturing Corporation, supra; Schriber-Schroth Co. v. Cleveland Trust Co., 311 U.S. 211, 220, 312 U.S. 654, 61 S.Ct. 235, 85 L.Ed. 132. Cf. Falkenberg v. Golding, 7 Cir., 195 F.2d 482, 485; Baker-Cammack Hosiery Mills, Inc., v. Davis Co., 4 Cir., 181 F.2d 550, 563; Smith v. Magic City Kennel Club, 282 U.S. 784, 790, 51 S.Ct. 291, 75 L.Ed. 707; Dolgoff v. Kaynar Company, D.C., 18 F.R.D. 424, 428, and pertinent cases therein cited.

The bell-mouth saturators which are said to infringe this patent are no longer in existence as they have been replaced by saturators of different type, principle and design.

Other matters which were presented at the trial and urged by counsel were considered by the Court but space will not permit a discussion thereof and, in view of the Court’s findings and conclusions, such discussion is unnecessary. Among these matters so presented are the following: (1) The presumption of validity arising from the issuance of the patent; (2) alleged commercial success of the bell-mouth crackerpipe; (3) the drawings, referred to as “The Preston Sketches”, made of Otto installation by Koppers; (4) increased volume of coke oven gas handled by bell-mouth cracker-pipe; (5) outline for lecture course given by Koppers’ employee; (6) defendants’ charge that bell-mouth saturator was on sale more than one year before Otto’s patent application; (7) defendants’ charge of indefiniteness of patent claims, etc.; (8) also the many cited court decisions.

Formal findings of fact and conclusions of law as to Patent No. 2,423,794 are as follows:

Findings of Fact

1. A prior-art saturator utilized a horse shoe shaped crackerpipe located in an oval tank, and the crackerpipe brought coke oven gas into contact with a bath of “mother liquor” to remove the ammonia from the coke oven gas;

2. The saturator described in finding No. 1 was widely used at least as early as 1917;

3. The saturator mentioned in finding No. 1 is described in this patent, column 3, lines 49-65, as the one on which Otto made his alleged improvement;

U. Otto’s alleged improvement consisted in substituting a bell-moutfy crackerpipe for the horse shoe cracker-pipe in the old saturator mentioned in finding No. 1;

5. During the prosecution of the application for this patent, the Patent Office was misled as to the following facts:

(a) The Patent Office was led to believe that there is something critical in the range of 4° to 15°, whereas there is not;

(b) The Patent Office was led to believe that there is something critical in locating the bell-mouth “slightly below” the surface of the bath, whereas there is not;

(c) The Patent Office was led to believe that there is something critical in the rate of gas flow recited in Claim 3 of the patent, whereas there is not;

(d) Incorrect statements were made to the Patent Office concerning prior-art patents;

6. Bell-mouth crackerpipes having different angles of slope of the bell-mouth and at different depths of immersion are shown in the prior art;

7. In Otto’s bell-mouth saturator installations, the depth of immersion of the bell-mouth varied between two inches and nineteen inches;

8. The record of this suit contains a number of prior-art patents that were not before the Patent Office and which are pertinent;

9. In the Wheeling bell-mouth saturator which is alleged to infringe Claims 1 and 3 of the patent, the bell-mouth had a slope of 3° from the horizontal;

10. Said Wheeling bell-mouth saturator did not have slots as specified in Claim 2 of the patent;

11. The Wheeling bell-mouth saturator did not have the rate of gas flow specified in Claim 3 of the patent.

Conclusions of Law

1. This patent in suit, No. 2,423,794, is owned by Otto, the plaintiff-patentee;

2. Consideration of the charge of infringement is here limited to the bell-mouth saturators which are no longer in existence, but which were formerly owned and operated by defendant Wheeling at Follansbee, West Virginia, in this judicial district, and which were installed there by defendant Koppers;

3. Otto did not make an invention when he replaced the horse shoe cracker-pipe in the saturator described in Finding of Fact No. 1 by the bell-mouth crackerpipe described in the patent;

4. There is nothing patentable in choosing an angle in the range of 4° to 15° for the bell-mouth;

5. There is nothing patentable in locating the bell-mouth “slightly below” the surface of the bath;

6. There is nothing patentable in providing a gas flow through the bell-mouth “in excess of two cubic feet per second per inch of length of the discharge edge of said surface”;

7. There is nothing patentable in combining two or more of the features described in Conclusions of Law Nos. 4, 5 and 6;

8. This Otto patent is invalid as involving no invention over the prior art of record in this suit;

9. The new evidence in this suit, including new prior art that was not before the Examiner, and expert testimony, overcome the presumption of validity;

10. This patent is not a pioneer patent and, if valid at all, is at best a narrow patent and its claims must be strictly construed;

11. The Wheeling bell-mouth saturator did not infringe because—

(a) Its bell-mouth had an angle of 3° from the horizontal and did not come within the 4° to 15° range recited in Claim 1 of the patent;

(b) It did not have the slots recited in Claim 2;

(c) It did not have the rate of gas flow specified in Claim 3 of the patent;

12. Defendants’ counter-claim for a judgment of invalidity and non-infringement of the claims of Patent No. 2,423,794 is well founded in law, on the basis of the facts established in this record, and plaintiff’s complaint, in so far as it pertains to this patent, will be dismissed. The judgment prayed for is proper and will be ordered.

U. S. Patent No. 2,599,067 (Otto Spray)

The application for this patent was filed on March 15, 1948, and United States Letters Patent No. 2,599,067 were duly and legally issued on June 3, 1952, to plaintiff as the inventor of the invention in production of ammonium sulphate therein described and claimed. The patent as issued contains nineteen claims and plaintiff charges that the defendants infringe basic method claims 1, 2, 4, 7 and 8 and basic apparatus claims 14, 15, 16, 18 and 19. The claims here involved are set forth in footnote. Plaintiff’s counsel withdrew the charge of infringement of all other claims by letter to the Court dated February 10, 1956, even though the pre-trial conference order set forth the charge of infringement of claims in addition to those appearing in footnote. The claim of infringement arises from an installation of coke oven gas, spray type, saturator equipment by defendant Koppers for defendant Wheeling in Brooke County in the Northern District of West Virginia. The installations were made during the year 1952 and continue in use.

This patent pertains to methods and apparatus for removing ammonia from coke oven gas by the use of liquid sprays and the production of ammonium sulphate. Otto testified that he made the invention therein described in May of 1946. Therefore, all public knowledge of the art prior to that date is pertinent to the issue of validity.

The claims in Otto’s original application ‘ were directed broadly to passing, by means of spray nozzles, mother liquor (saturated acidulated ammonium sulphate liquor) through coke oven gas in an unobstructed scrubbing space, passing coke oven gas through that space, stirring the supersaturated mother liquor in a crystallizing pool, removing the large crystals of ammonium sulphate, and respraying the mother liquor, containing entrained crystals, through the scrubbing space. Prior to the filing of this original application for letters patent, Otto filed other applications concerning the same subject matter and bearing the numbers and the respective filing date of each as follows:

Application 659,444 filed April 4, 1946; Application 668,392 filed May 9, 1946; Application 674,334 filed June 4, 1946; Application 720,593 filed January 7, 1947; Application 771,196 filed August 29, 1947; Application 3,133 filed January 19, 1948.

The prosecution of the application for this patent in suit continued over a period of approximately four years. Otto’s original claims and numerous amended claims were rejected by the Patent Office Examiner and were canceled by Otto. The specification was amended and revised and the claims were rewritten to distinguish from the prior art cited by the Patent Office. The prosecution of the application was interspersed with numerous personal interviews and repeated long arguments.

The inventive concept of producing ammonium sulphate by spraying saturated acidulated sulphate liquor into a gas stream passing through an unobstructed scrubbing space in a saturator by means of spray nozzles, thus causing the falling sprayed liquor to contain solid crystals of ammonium sulphate, was disclosed in Otto application 674,-334, filed June 4, 1946.

The full invention described and claimed in patent 2,599,067 was reached as the culmination of the successive inventions disclosed in these earlier Otto co-pending applications. This patent' was granted after examination and consideration of the prior art which is shown in the file history. The rejections of certain claims by the Examiner were reviewed by the Board of Appeals.

The following references are of record in the file of this patent:

United States Patents

Number Name Date

441,106 Monsanto Nov. 18, 1890

1,799,478 Peebles Apr. 7,1931

1,932,674 Pyzel Oct. 31, 1933

2,000,038 Schwalenbach May 7, 1935

2,035,441 Allen et al. Mar. 31, 1936

2,045,301 Danger June 23, 1936

2,288,667 Allen et al. July 7, 1942

2,375,922 J eremiassen May 15, 1945

2,409,790 Otto Oct. 22, 1946

2,424,205 Otto July 15, 1947

2,424,207 Otto July 15, 1947

2,450,095 Seebold Sept. 28, 1948

2,482,643 Tiddy Sept. 20, 1949

2,549,848 Otto Apr. 24, 1951

Other References

Fessenden, The Register of Arts, published in 1808 (page 87), C. & A. Conrad & Co., Philadelphia.

Defendants, in their amended answer, deny validity of the invention claimed, alleging that every material and substantial part thereof was disclosed in publications and patents prior to Otto’s alleged invention, and was patented or described in printed publications or in public use in this country more than one year prior to the application for this patent, as shown by the following:

“Patents”

Brunck U. S. 824,092 Patented June 26, 1906

Doherty U. S. 997,908 “ July 11, 1911

Bosch U. S. 1,029,528 “ June 11, 1912

Eneas U. S. 1,101,264 “ June 26, 1906

Becker U. S. 1,307,534 “ June 24, 1919

Becker U. S. 1,375,483 “ April 19, 1921

Becker U. S. 1,654,159 “ Dec. 27, 1927

Becker U. S. 1,747,616 “ Feb. 18, 1919

Berkhuijsen U. S. 1,985,010 “ Dec. 18, 1934

Berkhuijsen Swiss 172,661 “ Oct. 31, 1934

Tiddy U. S. 1,997,757 “ April 16, 1935

Jeremiassen U. S. 2,375,922 “ May 15, 1945

“Publication”

Hutte Handbook (German) Published in 1927 by Verlag VonWilhelm Ernst and Sohn, Berlin

“Prior Inventor”

Charles E. Underwood Bethlehem Steel Co. Bethlehem, Pennsylvania

“Prior Public Use”

Bethlehem Steel Co. Bethlehem, Pennsylvania

Koppers and Wheeling contend: That the Patent Office was misled by Otto’s incorrect argument concerning “whirling sprays”; that there was nothing novel or inventive with Otto in 1946 in the use of liquid sprays; that Koppers had used sprays in saturators before 1946; that there was no invention in scrubbing coke oven gas with sprays in an unobstructed space; and that there was nothing novel or inventive in spraying mother liquor that contained ammonium sulphate crystals. It is the position of these defendants that this invention claimed by Otto was merely a “non-inventive” engineering evolution, using methods and apparatus known in the prior art.

It is a well established rule of law that the grant of the patent is prima facie evidence of its validity. 35 U.S.C.A. § 282; Diamond Rubber Co. of New York v. Consolidated Rubber Tire Co., 1911, 220 U.S. 428, 434, 31 S.Ct. 444, 55 L.Ed. 527; Baker-Cammack Hosiery Mills v. Davis Co., 4 Cir., 1950, 181 F.2d 550, 564, certiorari denied 340 U.S. 824, 71 S.Ct. 58, 95 L.Ed. 605; Chesapeake & Ohio Ry. Co. v. Kaltenbach, 4 Cir., 1938, 95 F.2d 801; McKee v. Graton & Knight Co., 4 Cir., 1937, 87 F.2d 262.

The presumption of validity is strengthened where the patent was granted by the Patent Office after consideration of, and extensive administrative proceedings concerning, the same prior art as that relied upon by the defendants, or similar thereto. Hall v. Montgomery Ward & Co., D.C., N.D.W.Va.1944, 57 F.Supp. 430; Modern Products Supply Co. v. Drachenberg, 6 Cir., 1945, 152 F.2d 203, certiorari denied 327 U.S. 806, 66 S.Ct. 964, 90 L.Ed. 1030; Hildreth v. Mastoras, 1921, 257 U.S. 27, 42 S.Ct. 20, 66 L.Ed. 112; Reynolds v. Whitin Mach. Works, 4 Cir., 1948, 167 F.2d 78, 83, certiorari denied 334 U.S. 844, 68 S.Ct. 1513, 92 L.Ed. 1768; Hoeltke v. C. M. Kemp Mfg. Co., 4 Cir., 1936, 80 F.2d 912, 919, certiorari denied 298 U.S. 673, 56 S.Ct. 938, 80 L.Ed. 1395.

The judgment of the Patent Office officials in granting the patent in view of the prior art is entitled to great weight and is to be overcome only by clear proof that they were mistaken and that there is a lack of patentable novelty. Hall v. Montgomery Ward & Co., supra; Gulf Smokeless Coal Co. v. Sutton, Steele & Steele, 4 Cir., 1929, 35 F.2d 433, certiorari denied 280 U.S. 609, 50 S.Ct. 158, 74 L.Ed. 652; Patterson-Ballagh Corp. v. Moss, 9 Cir., 1953, 201 F.2d 403; Lever Bros. Co. v. Procter & Gamble Mfg. Co., 4 Cir., 1943, 139 F.2d 633, 640.

However, it is well established also that, even though the patent is presumed to be valid, the presumption may be overcome by new references to prior art not considered by the Patent Office. Todd v. Sears Roebuck & Co., 4 Cir., 1954, 216 F.2d 594; Gomez v. Granat Bros., 9 Cir., 1949, 177 F.2d 266; Friend, Inc., v. Walsh, 2 Cir., 1944, 141 F.2d 180.

From the record in this case, from the file history of proceedings before the Patent Office Examiner and the Patent Office Board of Appeals, from written briefs and arguments appearing in the file wrapper identified as Plaintiff’s Exhibit 1, and from the briefs and arguments submitted here, this Court concludes that Otto’s concept of his invention can be simply described as follows: Passing through and from a spray nozzle or spray nozzles, under pressure, an acidified saturated solution of ammonium sulphate (containing entrained ammonium sulphate crystals) in the form of a finely divided spray through coke oven gas containing ammonia while the gas is being pumped or forced through an unobstructed space in what is commonly known to the art as a saturator.

On page 34 of plaintiff’s main brief appears this heading: “The Disclosure of Patent 2,599,067”. Then near the bottom of the same page and continuing on page 35 appears the following:

“The particular spray disclosed in the drawings and specification of Patent 2,-599,067 is a ‘whirling spray’, defined as the type of spray produced by a Spraco nozzle such as shown in the Eneas Patent 1,101,264 (PX2; PX26A and 26B).

“Unobstructed space is disclosed as a space in which there is no obstacle to impede the gas flow from its inlet to its outlet * * *.

“The sprayed liquor with which Dr. Otto is concerned is an acidified saturated solution of ammonium sulphate containing entrained crystals.

“It is important to remember these three distinctions in examining the prior art. It will then be clear that no patent nor publication nor prior use discloses a saturator embodying these three features.” (Emphasis supplied.)

It appears clearly that Otto did not invent the type and kind of spray nozzles used in his patented method of spraying the ammonium sulphate solution through the coke oven gas. He purchased these on the open market from the manufacturer and these spray nozzles themselves are described in U. S. Eneas Patent 1,-101,264, and further described in pages from a catalogue of the manufacturer, Spray Engineering Co., of Somerville, Massachusetts, submitted to the Patent Office Examiner at an oral interview on August 1, 1950, and shown in Plaintiff’s Exhibit No. 2. Excerpts from Otto’s testimony on cross-examination, taken from pages 199 and 200 of the transcript, are quoted as follows:

“Q. * * * What do you mean and what do you understand by the word ‘spray’ in your patent? A. A subdividing of liquor, or a subdividing of a stream of liquor in small particles.”

******

“Q. You didn’t invent anything yourself in regard to sprays or spray nozzles, so far as your patent on the spray type saturator is concerned, did you? A. No. In connection with the spray type saturator, no, I did not invent a new design of a spray.

“Q. As a matter of fact, the sprays that you used and referred to in your patent, and that you use in your saturators, had been- on the open market and on sale long before your alleged date of invention in the spray patent, is that right? A. That's right.

“Q. And you simply bought them up yourself and put them in your saturator, so to speak? A. That’s - right.

“Q. And you can buy them— they will give you most any kind of spray you want — can’t you — coarse ■ sprays, fine sprays? A. That’s right.

“Q. Streams, mists, atomizers or . whatnot? A. That’s right.

“Q. And that was all well long before anything you claim in either patent? A. That’s right.”

Further excerpts from Otto’s testimony on cross-examination, beginning on page 209 and continuing through page 212, follow:

“Q. Now, Doctor, the essential feature of the Otto spray saturator, as you understand it, is the spraying of sulphuric acid through an unobstructed space through which coke oven gas passes, isn’t it? A. This spraying is not of sulphuric acid. The spraying of an acidified ammonium sulphate solution through an unobstructed space.

“Q. Well, as I understand it, you have modified my statement by defining the liquid that is sprayed to be an acidified solution- of sulphuric acid .containing ammonium sulphate? A. That is right.”

******

“Q. Now the liquid you are talking about is mother liquor that has previously passed through the saturator and has been drawn off at some place and then is recirculated. Isn’t that right? A. That is right.

“Q. So that the essential feature then is spraying liquor containing sulphuric acid and ammonium sulphate crystals through coke oven gas. Is that right? A. Not mainly sulphuric acid, but mainly mother liquor containing crystals, this liquor being acidified with sulphuric acid. Sulphuric acid is a small proportion of this liquor.

“Q. Well, the liquor that is circulated in your spray type of saturator is simply a part of the mother liquor that, has already been used, is it? A. That’s right.

“Q. Plus the addition of some sulphuric acid? A. That is right.

“Q. To make up for what has been lost by ammonium sulphate crystals that have been removed?

A. That is right.”

******

“Q. The same kind of mother liquor also resulted from the use of the crackerpipe saturator? A. It is the same type of mother liquor as in. a crackerpipe saturator.

“Q. So what I am coming at and getting to, with some circumvention as part- of my mistake, sir, is that the real crux of the invention which you are asserting is the spraying of a certain type of liquor through coke oven gas containing ammonia for the purpose of removin