Full opinion text
COLEMAN, District Judge. This is a patent infringement suit. The plaintiff, Sales Affiliates, Inc., a New York corporation, is the assignee of' United States patent No. 2352524, granted June 27, 1944, on application of June 20, 1938, to Ralph L. Evans and Everett G. McDon ough, for a depilatory, that is, for an agent for the removal of hair from the human body. Schering Corporation, a New Jersey company engaged in the business of manufacturing and selling cosmetic preparations, is the exclusive licensee of the plaintiff under this patent for making and selling a depilatory known as IMRA. One of the defendants, Hutzler Brothers, Company, a Maryland corporation, sells a depilatory known as SLEEK, manufactured by Elizabeth Arden, Inc., a New York corporation. Plaintiff first sued -Hutzler Brothers Company, claiming- infringement of the patent. .Shortly thereafter, a similar suit was brought by plaintiff against Carter Products, Inc., a Maryland corporation, which makes and sells a depilatory known as NAIR. The Schering Corporation, at the commencement of the trial of the present suit, petitioned for leave to intervene, but this right was denied because in contravention of the express provisions of the license agreement between that corporation and the plaintiff; and also because of the absence of any showing'that the Schering Corporation’s rights under that agreement would not be adequately protected, even though, it was denied the right to intervene at this time. The two,,suits were, consolidated and tried together. Both defendants have asserted the usual defenses of (1) non-infringement, and (2) invalidity of the patent. The patent embraces 17 claims. However, only six are in suit,' namely, Nos. 2, 6, 11, 12, 13 and 17, and counsel for defendants virtually conceded infringement- of all of them in the course of the hearing, but deny their validity. . The novelty claimed for the patent is that the compound which it embraces is the first chemical depilatory to combine all of the following characteristics: (1) absence of objectionable odor; (2) nonirritating and harmless to the human- skin; and (3) quick and completely effective in its depilating results. The alleged invention may best be understood by quoting the following from the specifications of the patent itself: “The practice of removing hair from, the skin of certain parts of the body has been followed for many years. Various methods such as shaving, abrading, plucking, electrolysis, etc., have been resorted to, but the method most popular for removal of .hair from the, arms, armpits, and legs, particularly of women, employs preparations whose chemical action on the hair fibre sufficiently weakens it so that the hair above the skin surface may be wiped or washed off in a few minutes after applying. These preparations are known as depilatories and are sold in liquid, paste or powder form. The latter is made into a paste by addition of sufficient water in order to be used. “These chemical preparations contain as their effective ingredients, one or more of the alkali or alkaline-earth salts of hydrogen sulfide. Such salts have a tendency to hydrolyze and have an appreciable vapor pressure due to the hydrogen sulfide gas. Their use in any product imparts to it the disagreeable odor that is reminiscent of rotten eggs. All attempts to mask the odor result in failure. The use of heavy perfume and gaseous absorbents, such as clays and charcoals, only serve to minimize the objectionable odor. If the alkalinity is increased, the odor is reduced but the possible danger due to irritation of the skin is increased. If the sulfide is oxidized to an odorless form, its odor is destroyed, but also the effectiveness of the product is lost. “Another disadvantage that accompanies the use of these sulfides is that when present in a paste they impart to it an unattractive greenish cast, probably due to the formation of insoluble colored metallic sulfides. “Besides the disgusting odor that accompanies the use of hydrogen sulfide salts is the fact that the liberated or free hydrogen sulfide that escapes into the room is toxic to breathe and although in such dilution it is probably not dangerous, nevertheless, together with its nauseating odor it has caused certain individuals to become ill. “Also the escape of this hydrogen sulfide gas into the home causes black coating of most metal utensils, such, for example, as silverware or jewelry. Also, it is retained and imparts its loathsome odor to fabrics and rugs, etc. “The object of our invention is the production "of depilating preparations which have none of these disadvantages. There are no objectionable odors, a white paste is produced, a delicate perfume may be used and silverware- or other metals are not tarnished if brought in contact with the preparation. Depilating preparations made in accordance with our invention will remove hair quickly (within 5 to 10 minutes), depending on coarseness of the hair, safely (without injury to the skin), and effectively (no stubble left). # * * * * * “A depilatory to achieve its purpose must destroy hair without damaging or even irritating the outermost layers of the skin. The difficulty of accomplishing this object appears almost insurmountable when one realizes the close chemical relation that exists between the outer skin (epidermis) and hair. Further, in a commercially successful preparation the depilatory must remove even the most resistant arid coarse hair and yet not injure or irritate the most delicate and sensitive skin. Further, the depilation must take place in a very short time, not to exceed about thirty minutes, not only because the user will be annoyed the longer the time but also because with longer contacts there is a tendency to do skin damage because of (a) penetration into and action on the skin of the depilatory solution and (b) evaporation of water from a paste depilatory to form a crust that abrades the tenderized skin on removal.” The further specifications of the patent are quite detailed and lengthy. Summarized, the alleged primary basic distinction between the depilatory covered by the patent and depilatories previously known, lies in the use of mercaptans instead of’ sulfides. Mercaptans may be broadly described as organic compounds having sulfide atoms. They are divided into two broad classes which are commonly spoken of as (1) simple mercaptans and (2) substituted mercaptans. A simple mercaptan is an organic substance stemming from an alcohol, in which the hydroxyl group has been replaced by one hydrogen sulphide group (HS). A substituted mercaptan is a simple mercaptan in which one or more of the hydrogen atoms have been replaced by some other atom or groups .of atoms. Substituted mercaptans are again divisible into (1) those of the non-polar group which in solution do not ionize, that is, do not, when put in solution, break down into electrically charged particles, both positive and negative, known as ions; and (2) those of the polar group which do ionize in solution. This latter group includes both (a) those of the acid-acting kind, and (b) those of the basic-acting kind. It is clear from the Evans and McDonough specifications that all of the aforementioned types of substituted mercaptans are intended to be included. Of the claims in suit No. 2 is the narrowest and No. 6 the broadest. We quote them both: “2. A depilatory , for use in removing human hair from the body, comprising a creamy preparation containing a substantial amount of a creamy non-depilating vehicle carrying thioglycollic acid, and an excess of an • alkaline reacting material, said creamy preparation being adapted to be spread upon the human skin and around the hair, the amount of thioglycollic acid being sufficient to render the hair removable after contact therewith within a short time and without irritation to the skin, and the alkaline reacting material being present to an amount sufficient to give the preparation a pH value between about 10 and 12.5.” “6. A depilatory for use in removing human hair from the body, comprising a creamy preparation containing a substantial amount of a creamy non-depilating vehicle carrying a mercaptan, and an excess of an alkaline reacting material, said creamy preparation being adapted, to be spread upon the human skin and around the hair, the, amount of mercaptan being sufficient to render the hair removable after contact therewith within a short time and without irritation to the skin, and the alkaline reacting material being present in an amount sufficient to give the preparation a pH value between 9 and about 12.5.” Breaking down claim 2, the narrowest of the claims in suit, into its component parts, we find that it calls for the six following things: (1) A substantial amount of a creamy non-depilating vehicle; (2) carrying thioglycollic acid (which is also known as mercapto-acetic acid) ; (3) an excess of an alkaline reacting material; (4) this creamy preparation being adapted for spreading upon the human skin and around the hair; (5) the amount of thiogiycollic acid being sufficient to render the hair removable after contact therewith within a short time and without irritation to the skin; and (6) the alkaline reacting material being present in an amount sufficient to give the preparation a pH value between about 10 and 12.5. It will be seen that the 'compound called for by the claim embraces two depilating ingredients: (1) the mercaptan, namely, thiogiycollic acid, and (2) an alkaline reacting material such as lime, which is the material especially recommended in the specifications. In addition to these basic ingredients there is the paste-forming ingredient which may be any one of many non reactive, insoluble powders, preferably, • as the specifications state, precipitated chalk, magnesium oxide, clays, talcs or pyrophyllites. Lastly, there is included a perfume material consisting of 1% or less of light compounded floral odors. If we separate the component parts of claim 6 as we have done those of claim 2 they will be found to be the same as those of claim 2 except that (1) no particular mercaptan is specified, and (2) the lower limit of the pH value (pH being, in chemistry, the measure of alkalinity, and pH 7 representing the neutral point between acid and alkaline) is reduced to 9 from “about 10”. Shorn of technical phraseology, hair is the outgrowth of the epidermis or the outer layer of the skin, containing neither blood vessels nor nerves, and is composed of a horny substance known as keratin. The function of the mercaptan is to weaken the keratin, and then it becomes the function of the other depilating ingredient, namely, the alkaline reacting material, to remove the hair which has thus been weakened. In depilatories where sulfides, instead of mercaptans are used, the sulfides perform the same function as mercaptans. The Question of Validity. (a) — Context of the claims. Since, as has been stated, the defendants rely primarily upon their contention that the patent is invalid and indeed virtually concede that, if valid, the claims in suit have been infringed by their products, it is appropriate to proceed at once to a consideration of the question of the patent’s validity. Defendants raise the question of validity on a number of grounds. We will take these grounds up separately and will first consider the contention that the claims in suit are invalid because indefinite and merely functional in terms, and, therefore, fail to meet the requirements of R.S. Sec. 4888, 35 U.S.C.A. § 33. R.S. Sec. 4888 provides that the description of the invention or discovery “and of the manner and process of making, constructing, compounding, and using it,” shall be “in such full, clear, concise, and exact terms as to enable any person skilled in the art or science to which it appertains, or with which it is most nearly connected, to make, construct, compound, and use the same; * * * and he shall particularly point out and distinctly claim the part, improvement, or combination which he claims as his invention or discovery. * * * ” Defendants assert that in order to meet these statutory requirements in the patent in suit, the critical formulation must be recited in the claims, and that they are not met by providing merely for “the alkaline reacting material being present in an amount sufficient to give the preparation a pH value between about 10 and 12.5”, as claim 2 recites, and as all of the other five claims likewise recite, except for some specified variation in the lower or upper pH range. It is claimed that this leaves too much for experimentation. Do other ingredients affect what is “sufficient” in a particular case? Does the amount that is “sufficient” change with the pH value of the particular “alkaline reacting material” used? No particular “material” is specified. Does the amount that is “sufficient” change with the particular mercaptan employed? Only claim 2 of all of the claims in suit specifies a particular mercaptan, namely, thiogiycollic acid, but even in that claim the amount is not specified. Similarly, the defendants emphasize that all of the six claims in suit recite, in substance, that the amount of mercaptan will “render the hair removable” or will “effect removal of the hair”, after contact within i “a short time”, and “without irritation to ' the skin”. What is “a short time” ? How much or how little irritation is permissible? How much mercaptan will remove hair within “a short time”? By stating the aforegoing questions and finding them, as defendants assert, unanswered by the words employed in the several claims, defendants argue that, therefore, the claims are invalid on their face, since they call merely for results anticipated, in purely functional language,— that they are too indefinite and do not define the metes and bounds of the alleged invention. In support of this contention, defendants quote the language of various decisions to the effect that no inventor may compel independent experimentation by others in order to ascertain the limits of his claims; that he may not broaden his claims by describing the product in terms of the function. The rule thus stated is basic in our patent law. The claims measure the invention. Paper Bag Patent Case (Continental Paper Bag Co. v. Eastern Paper Bag Co.), 210 U.S. 405, 28 S.Ct. 748, 52 L.Ed. 1122; General Electric Co. v. Wabash Appliance Corporation, 304 U.S. 364, 58 S.Ct. 899, 82 L.Ed. 1402; United Carbon Co. v. Binney & Smith Co., 317 U. S. 228, 63 S.Ct. 165, 87 L.Ed. 232. Therefore, we accept it as applicable to the present case. However, it is equally axiomatic that each and every claim of a patent is to be read and interpreted in the light of the specifications set forth in the patent; and that while a material deficiency in the language of a claim may not be supplied merely by reference to supporting provisions in the specifications, it is, nevertheless, true that, depending upon the particular character of the alleged invention, there may be certain things set forth in the specifications that need not be embraced in the claims themselves but which, when read with the claims, make the latter adequate under the statutory requirements. Although specifications may not enlarge a claim, they may explain it. See General Electric Co. v. Wabash Appliance Corporation, supra; Schriber-Schroth Co. v. Cleveland Trust Co., 311 U.S. 211, 61 S.Ct. 235, 85 L.Ed. 132; United Carbon Co. v. Binney & Smith Co., supra. Applying the rule as thus stated to the claims in suit for the purpose of determining whether they are too indefinite or functional in their terms, we conclude that they are not. In every chemical patent of the general character of the one in suit, in the very nature of things certain leeway must be permitted with respect to the amount of a particular ingredient where, as here, the use of any one of various ingredients well known in the art and embraced in the generic term employed in the claim to cover them, is permissible. As above pointed out, defendants urge that with respect to the alkaline reacting material, it is not enough to say that the amount of that material shall be “sufficient” to give the preparation the specified pH value. However, the amount is, in fact, specifically defined by a formula in the specifications. It is stated that “it is desirable that the concentration of the alkaline material in solution be not greater than twice the equivalent concentration of the mercaptan (and the acid groups it contains). For. example, in one liter of solution, if with 0.2 mole of mercapto-acetic acid is used 0.5 mole of sodium hydroxide (1.25 equivalents) good results are obtained, yet a smaller amount of mercapto-acetic (0.1 mole) with the same amount (0.5 mole) or (2.5 equivalents) of sodium hydroxide concentration gives skin irritation and damage.” Next, with respect to the complaint that no particular alkaline reacting material is specified, this is likewise lacking in merit, because it must be borne in mind that all such materials, their properties and characteristics are well known in the art, and, besides, the specifications are replete with an enumeration of these materials, and with an analysis of their respective attributes, advantages and disadvantages if employed in the formula. At the end of the specifications, one particular illustrative formula is set forth, giving the precise type and quantities of every ingredient embraced in it, following which is this statement: “While we have described examples of our invention and have outlined advantages of our invention over the art, we do not wish to limit ourselves to the exact materials or preparations outlined in the proceeding. A variety of materials of like or similar properties may be used in lieu of those described herein and the preparations may be widely varied, without departing from the scope of our invention or the spirit of the appended claims.” As we have already indicated, the same argument is made against the recital in the claims with respect to the required amount of mercaptan necessary to accomplish complete depilation in -a short time, without irritation to the skin; also, that there is a fatal defect in the claims in not defining what is meant by “a short time”. But, likewise, we feel that the argument of indefiniteness with respect to these points is no more tenable than with respect to the alkaline reacting material, because we find that the .specifications not only supply the so-called gaps but we believe that they are gaps which are permissible.in the claims in dealing with chemical formulas of the type here involved. As respects the requisite amount of mercaptan, the■ specifications state: “We have found that when the concentration of the mercaptan is less than 0.1 mole per liter of solution it is necessary for us to increase the alkalinity to such a high concentration in order to effect hair destruction that skin damage and irritation results. Further, we have found that the mercaptan need not exceed 1.5 moles per liter. * * * The most desirable results are achieved when the solution contains about 0.5 mole of the mercaptan per liter of solution.” Insofar as the failure to state in the claims what is meant by the phrase “short time” when used in connection with the depilating process, again we believe that it is not a fatal defect to require reference to the specifications in order to ascertain the meaning of this phrase. The specifications state that “Depilating preparations made in accordance with our invention will remove hair quickly (within 5 to 10 minutes), depending on the coarseness of the hair, safely (without injury to the skin), and effectively (no stubble left) .7 It would be carrying the requirements of definiteness to an absurd point, we think, to' say that with respect to a chemical formula of the type and for the use specified, the results claimed for that use are accomplished within a maximum number of minutes' in every application. We know of no precedent for such requirement. " [9] The second major argument of defendants that the claims in suit are invalid because too indefinite, is based upon the facts that the claims (except claim 2) embrace, by their broad language, whole classes of mercaptans in which fall an unlimited number of types not covered by the specifications of the patent. The specifications analyze and discuss two types of mercaptans, the first being described by the experts who testified for both the plaintiff and defendants by the term “simple mercaptans”, and the second, by the term “substituted mercaptans”, both of which we have already defined. The specifications state that “Simple mercaptans are of no value commercially since they possess a nauseating odor, far greater, in most instances, then hydrogen sulfide.” Thus, simple mercaptans are written out of the patent as not being a permissible,ingredient of the prescribed formula. As for the other type of mercaptans', namely, substituted mercaptans, several are specifically referred to, and, as we have already seen, one of them, belonging to the acid-acting groups and described in the specifications as being particularly effective for the desired purpose, is included in the illustrative formula given at the end of the specifications, namely, mercapto-acetic acid (thioglycollic acid); Turning to the six claims in suit, we may divide them into two groups, in the first of which fall the broadest claims, Nos. 6 and 17, and in the second, the narrowest, Nos. 2, 11, 12 and 13. Claim 6 Uses the broad term “mercaptan” without more description. Claim 17 uses the term “salt'of mercaptan” without further description. Thus, both of these claims, by reason of their broad scope in this respect (the term “salt of mercaptan” embracing salt of a simple mercaptan) do, by' their very language, include those' mercaptans which, by the express statement in the specifications above quoted, are declared to be ineffectual as ingredients for the production of the depilatory as contemplated by the patent. Accordingly, we find that these two claims, Nos. 6 and 17, must be held to be invalid because too broad and inconsistent with the specifications. Turning to the remaining four claims which we have grouped together, i.e., claims 2, 11, 12 and 13, we need not repeat what we have already said to indicate that claim No. 2 is not defective, as are claims 6 and 17, with respect to its reference to mercaptans, because it goes to the other extreme and specifies only one mercaptan, namely, thioglycollic acid. Claims 11, 12 and 13, each call for “a substituted mercaptan”. This is attacked by defendants on the ground that the specifications of the patent refer to only three specific “substituted mercaptans”, viz., beta-mercaptoethanol, thioglycollic acid (mercapto-acetic) and beta-aminoethylmercaptan; and that except for the additional reference.to two mercaptans, designated as simple ones, i.e., ethyl mercaptan, and benzyl mercaptan, (which are stated to be unsatisfactory), the specifications fail to name any other mercaptans, and refer merely to “groups”, such as “carboxyl groups”, “amino groups”, “hydroxy group”, and “polar” and “non-polar” groúps. From this it is argued that only by experimentation can it be deter-’ mined what types of mercaptans will work. It is to be noted that defendants’ chemist, contrary to plaintiff’s chemist, put benzyl mercaptan in the class of simple mercaptans. It is true, as has already been explained, that R.S. Sec. 4888 requires an inventor to inform the public of the limits-of his monopoly, and that his claims must measure the invention. But again, we believe that the degree of precision required in a claim, with respect to complete enumeration of all the various ingredients contemplated by a chemical formula, must depend somewhat, upon the extent to which the properties of those ingredients are already known to the chemist. The chemists who testified on both sides in the present case stated that, at the present time, the field of mercaptans is still unexplored to such an extent that they could not state with exactness how many mercaptans were actually known, but they were in agreement that the division of mercaptans into the two groups of (1) simple mercaptans, and (2) substituted mercaptans, was proper. The specifications of the patent here in suit expressly exclude the .former from being appropriate ingredients under the specified formulas. We do not believe, in view of the present state of chemistry with respect to mercaptans, that the rule as to definiteness is violated by permitting the patentees in the present case to' embrace in a claim under the broad class terminology of “substituted mercaptans”, all mercaptans which they believe to be operative, especially since the specifications analyze and explain why certain of those mercaptans are believed to be best adapted to accomplish the desired result, and even though, as the evidence disclosed, some of them were not so adapted. We now turn to a consideration of another ground on which defendants argue that the claims in suit are invalid, 'namely, that the mere control of the pH value of a depilatory, through the purported discovery of an optimum of alkalinity, does not constitute patentable invention, and that invention cannot be predicated Upon any other ground. The specifications of the patent recite that “preferably the pH value should not be less than pH 9.0 and no greater than pH 12.5. Below pH 9.0 the depliating action is too slow, and as the pH increased beyond pH 12.5 the skin damage becomes increasingly more pronounced and . the skin irritation more severe.” In short, this is an expression in chemical terms of the patentees’ conclusion as to how high the alkalinity of their formula might be raised in order to insure' quick and complete depilation while, at the same time, not being, so high as to cause irritation to the human skin. Thus, of the six claims in suit,' the four which, as just stated, are sufficiently definite in their terminology, namely, claims 2, 11, 12 and 13,' specify a pH value not greater than 12.5 and not less than 9 in the case of claims 11, 12 and 13, and not less than 10 in the case of claim 2. But defendants assert that the purported discovery of an optimum of alkalinity does not constitute patentable invention, for the reason that the prior art clearly disclosed that a depilatory should not irritate the skin of the user and that a solution having an upper pH value of about 12.5 will not irritate the skin of the average person ; that there is express recognition by the patentees of prior knowledge of the danger of irritation in a depilatory by their statement in the specifications; that whether or not an alkaline solution irritates the skin depends on numerous factors, among which are (a) the sensitiveness of the user’s skin, and (b) the length of time the skin is exposed to the solution; and the fact that the patentees actually presented claims in their application which called for an upper pH value of 13 is tantamount to an admission that they believed there was nothing critical about a pH value of 12.5 as compared to 13. * Assuming for the moment that the discovery of an optimum of alkalinity may not, per se, constitute patentable invention because of prior art disclosures, it does not follow that these four claims are for this reason invalid, since each of them embraces a combination of ingredients, and the question is, therefore, whether the patentees were the first to discover and put this combination to successful use, even though all of the ingredients may have previously been known to the art, and even though some of them had been previously used in similar, provided not in the same or equivalent combination, unless the patentees and, therefore, their assignees, the plaintiff, are not permitted to claim that novelty in the combination rests upon anything but control of the upper pH value. Defendants claim that the plaintiff is so restricted in the present suit, namely, that it is estopped from taking any other position. In support of this argument, defendants rely upon the history of the patentees’ application through the Patent Office and the issuance of the patent, which, as defendants assert, indicates that all four of the claims of the patent now under consideration were granted by the Patent Office Examiner solely upon a mistaken view that there was novelty over the prior art only in defining an optimum of alkalinity, and that the patentees, having accepted this position of the Patent Office Examiner and embodied it in their amended claims, the plaintiff is now estopped from adopting any other position. In order to determine whether or not this argument of defendants’ is sound, it is necessary to review the action of the Patent Office Examiner. The application for the present patent was filed June 20, 1938, although, as stated in the patent, this application was a continuation, in part, of patentees’ application, serial No. 167934, which had been filed October 8, 1937, but thereafter abandoned. The progress of the later application through the Patent Office was slow and protracted due, to some extent, to the fact that it was placed in interference with an application by one Karel Bohemen, a Dutch subject, which had been filed on July 24, 1937, and which corresponded to a French patent, No. 824,804, issued to one William Fletcher. This proceeding, however, was terminated by settlement between the parties, Bohemen withdrawing in favor of Evans & McDonough in consideration of his getting a license under their patent from the present plaintiff. Omitting the major portion of the Patent Office chronology as disclosed by the file wrapper with 'respect to the application for thé present patent, because believed to be immaterial to the precise issue now before us, we turn to the letter dated December 13, 1943, which the Patent Office • Examiner addressed to the patentee, and upon which defendants primarily rely. This letter reads as follows: “Responsive to amendment filed Dec. 4, 1943. “Claims 34, 39, 40, 41, 43 and 48 to 59 are now in this application. “ — a—should be inserted after ‘carrying’ in line 3 of each of the newly presented claims 48 and 50 to 59 and in line 4 of claim 49. “Claims 48, 52, 57, 58 and 59 [which became nos. 6, 10, 15, 16 and 17, respectively, of the patent] are rejected as failing to define patentability over Turley. These claims do not recite any upper limit for the pH and so will read on the extremely alkaline compositions used by Turley. In this connection it should be noted that applicants are not the first to discover the depilating action of mercaptans, for such action is taught by Turley. Applicants have only discovered that when the pH is within a certain range (between 9 and 12.5) the preparation is a safe depilatory for human use. Hence the omission of the upper limit of the pH is an omission of one of the essential, basic features of applicants’ invention; and such amission renders the claims unpatentable over Turley. Note that there is nothing to indicate that Turley’s compositions would not be effective and relatively safe depilatories for human use if they were removed after an extremely short period of time. “Claims 34, 39, 40 and 41 [which had been allowed July 10, 1943, and ultimately became claims 1, 2, 3 and 4, respectively, of the patent] and 43 [not previously allowed, and which became No. 5 of the patent] are deemed allowable while claims 49, to 51 and 53 to 56 will be allowable when amended as suggested above. [The amendment is the mere insertion of a preposition as above referred to.] “A clear issue having been reached, this rejection is MADE FINAL.” (Italics inserted). Upon receipt of the aforegoing letter, patentees amended the five claims that had been rejected by the above letter, namely, claims 48, 52, 57, 58 and 59, (which became nos. 6, 10, 15, 16 and 17, respectively, of the patent) because of their failure to specify in each of them the upper limit of the pH, by inserting this specification. Thereupon, these claims were allowed. Also, the other claims with which we are not here concerned were allowed upon the minor grammatical change being made as suggested by the Examiner. As a matter of fact, this same minor change was made in all of the claims that had not previously been allowed. In order to determine whether, as defendants assert, the plaintiff is estopped from saying that there is novelty in this combination other than such as may be embraced solely in the control of the upper pH limit, it is necessary first to analyze the contents of the aforegoing letter of the Examiner, with direct relation to what the Examiner had previously ruled with respect to other claims embraced in the patent application, and to understand the character of those claims. It is to be noted that by his letter the Examiner rejected claims 48, 52, 57, 58 and 59, which, as already stated, ultimately became claims 6, 10, 15, 16 and 17, respectively, of the patent; and that also, he “deemed allowable” claims 34, 39, 40 and 41, which, as we have also already explained, had previously been allowed and ultimately became claims 1, 2, 3 and 4, respectively, of the patent. When originally allowed, these four claims read precisely as they did when the Examiner ruled upon them in his letter of December 13, 1943, just analyzed; and it is significant to note that all but one of them, namely, claim 34 (which, unlike all the other claims ultimately allowed, calls for one specific formula, and which became claim 1 of the patent), contained a recital of the upper pH limit. Also, claims 49, 50, 51 and 53, 54, 55 and 56, which, by the Examiner’s letter were allowed upon a minor grammatical change being made, likewise'contained the same pH limit and became claims 7, 8, 9, 11, 12, 13 and 14, respectively, of the patent. Also, claim 43, which became claim 5 of the patent and which, as we have seen, was first allowed by the Examiner’s letter of December 13, 1943, had originally contained the same pH limit. It will thus be seen that the Examiner, by his ruling that the omission of the upper limit of the pH from certain of the claims specified in his letter, was a fatal omission, was harmonizing his position regarding these claims with the position he had taken with respect to previously allowed claims. Defendants assert that the Examiner’s letter indicates beyond question that the control of the pH value was the sine qua non of the Examiner’s allowance of the claims; that the plaintiff must stand or fall upon this construction of the claims as adopted by the Examiner, with the result that the claims must be held invalid because the mere control of the upper pH value of a depilatory, whether 12.5 or any other amount, is not invention, since the prior art, particularly as disclosed by the patent to Turley, which, as defendants assert, the Examiner mistakenly supposed embraced a higher pH than 12.5, taught precisely the same control. Conceding, as we believe must be done for reasons which we will hereinafter give in dealing specifically with the prior art patents, that the Examiner was, as defendants claim, in error with respect to his interpretation of the Turley patent in its relation to the upper pH limit, we are, nevertheless, not convinced that defendants are correct with respect to the, conclusion that must follow from the Examiner’s error. In the first place, it is necessary to bear in mind that we are here dealing with claims that involve a combination of ingredients, — that it is the entire combination, and not any single ingredient upon which novelty may rest, — a combination that, to be patentable, had to be new in the sense that no one had previously disclosed this same combination of ingredients, even though all the ingredients and their respective properties were well known in the prior art. Therefore, even if we assume that the Examiner’s letter must be interpreted as though he considered that invention lay solely in the control of the. upper pH limit, nevertheless, we do not think that the plaintiff is necessarily thereby estopped from asserting a different position. We say this because the plaintiff claims, and we believe has a right to claim, that the allowed claims comprise a combination not previously disclosed, and that it is not restricted to proof that 'novelty lies solely in one element of the combination. In other words, plaintiff is not prevented from insisting that the actual invention is in fact broader or different from what the Patent Examiner had supposed. Our conclusion is, we believe, supported by numerous decisions. For example, Egry Register Co. v. Standard Register Co., 6 Cir., 267 F. 186, certiorari denied, 254 U. S. 642, 41 S.Ct. 14, 65 L.Ed. 453, was a case involving alleged infringement of a patent relating to autographic registers for making a plurality of shipping bills, sales slips, etc. The claims of the patent here in suit involved two elements: a feeding device and a device for facilitating the tearing off of the sheets. In rejecting the argument of the defendant that the plaintiff was estopped from claiming the benefit of the feeding device as an element of his claims, the Circuit Court of Appeals for the Sixth Circuit.said, 267 F. at page 190: “We think the claims in suit, when read in connection with the specification, should be construed as claiming the invention of the patent as above defined, viz. the combination of the feeding device disclosed and the cutting-off mechanism described. Nor do we find anything in the Patent Office history which estops the patentee from claiming the benefit of the feeding device as an element of the combination of these claims. The fact that the patentee acquiesced in the rej ection of claims 1 to 4, inclusive, as originally presented — which claims were confined entirely to the feeding mechanism — does not bar him from relying upon the claims now in issue, which are combination claims and include, not only the feeding mechanism, but the added element of the tearing-off mechanism. It is almost a commonplace that a new combination of elements, old in themselves, but which produce a new and useful result, amounts to invention.” International Cellucotton Products Co. v. Sterilek Co., 2 Cir., 94 F.2d 10, involved circumstances very similar to those before us. This was a suit for alleged infringement of a patent issued to one Bauer for a machine for making catamenial pads. When Bauer applied for his patent, the Examiner cited against his claims another machine. To escape this reference, Bauer thereupon limited his claims to a machine in which gauze ran at right angles to the filler web. The defendant argued that Bauer, by so limiting his claims in the Patent Office, had conceded that the prior art anticipated his claims with the sole exception of this interpolated feature. However, the Court rejected this argument of defendant (although subsequently the Bauer patent was held invalid on another ground), saying, 94 F.2d at page 12: “When an inventor consents to limit his monopoly, there is no reason in fact to impute to him the belief that his only patentable advance lies in the element so introduced. He may merely think that he still retains enough for practical purposes, and that the examiner’s insistence does not justify the expense of an appeal. Nor. is there, any reason to impose upon him the same consequence as though he had formally so conceded; it is enough that he has freed the art except as the claim reads, and that he has surrendered any power under the doctrine of equiva-’ lents to resume what he has given up. He has done nothing which need prevent him from insisting in support of the claim as allowed that his invention was broader than the examiner supposed; he is not confined to the examiner's reasoning or committed to his mental processes. United .Chromium v. International Silver Co., 2 Cir., 60 F.2d 913, 915. We cannot therefore recognize the ‘Johnson & Johnson machine’ for any purpose whatever; it was not proved as a prior use, and until it was, the defendant might not rely upon it.” (Italics inserted.) To the same effect is France Manufacturing Co. v. Jefferson Electric Co., 6 Cir., 106 F.2d 605, certiorari denied 309 U.S. 657, 60 S.Ct. 471, 84 L.Ed. 1006, rehearing denied 309 U.S. 696, 60 S.Ct. 589, 84 L.Ed. 1036. Defendants rely, as authority for estoppel, on Boynton v. Chicago Hardware Foundry Co., 77 F.2d 799, a decision of the Seventh Circuit Court of Appeals. There the patentee relied on three claims which had been rejected by the Patent Office for lack of invention, but which were later allowed after amendment. The patentee then contended that his invention lay solely in that portion of his amended claims which, as originally submitted, had been rejected by the Examiner. The following taken from the Court’s opinion discloses the precise situation in that case (77 F.2d at page 801) : “The file wrapper discloses that certain claims of appellant which were rejected by the Patent Office are precisely the same as those now in issue, with the exception of certain clauses relating to the joints separating the inlays. These are indicated by our italics in foot-note 1. They were rejected for lack of invention over Snedekor, No. 457,975, which discloses molding over a rubber matrix. In that ruling appellant acquiesced by canceling original claims 2, 4, 6 and 7, and amending original claims 1, 3 and 5 by adding the italicized portions above referred to, and renumbering them respectively 1, 2 and 3. Original claims 2, 4 and 6 are precisely the same, respectively, as the present claims 1, 2 and 3 except that the latter contain the italicized portions referred to. In Morgan Envelope Company v. Albany Perforated Wrapping Paper Company, 152 U. S. 425, 14 S.Ct. 627, 629, 38 L.Ed. 500, the Court said: ‘But the patentee having once presented his claim in that form, and the Patent Office having rejected it, and he having acquiesced in such rejection, he is, under the repeated decisions of this court, now estopped to claim the benefit of his rejected claim or such a construction of his present claim as would be equivalent thereto.’ That principle would seem to be applicable regardless of 'whether the Patent Office was right or wrong in rejecting the original claim. Vanmanen v. Leonard, 6 Cir., 248 F. 939. Under those rulings we think appellant is estopped to claim invention on a rubber or flexible matrix, unless by combination with other matters contained in the amendments a new result is produced, or' an old result is produced in a more facile, efficient or economical manner. We are convinced, however, that no such result was produced. The rubber or flexible matrix was not new, nor was the filling of the joints, which was merely permissive on the part of Boynton. Indeed, there seems to be no functional relationship between the two steps, and no modification of the old use of either.” In the present case, excluding claims 6 and 17 as we do, because, as already explained, they must be held invalid for ind'éfiniteness, there remain four other claims in suit, nos. 2, 11, 12 and 13, which were allowed by the Examiner precisely as originally drawn (with the exception of a minor grammatical change), and in which the patentees here contend their invention lies. There is thus a definite distinction between the situation in the pre.sent case and that in the Boynton case, namely, there, the patentee rested his claim of invention exclusively upon the elements of his rejected claim, whereas in the present case, the plaintiff relies upon the allowed claims, each one of which, plaintiff contends, discloses a now combination of which the specified pH limit is merely a part. Similarly, such cases as Morgan Envelope Co. v. Albany Perforated Wrapper Paper Co., 152 U.S. 425, 14 S.Ct. 627, 38 L.Ed. 500 and Vanmanen v. Leonard,. 6 Cir., 248 F. 939, cited in the Boynton case,, are to be distinguished; as are also Schriber-Schroth Co. v. Cleveland Trust Co., 311 U.S. 211, 61 S.Ct. 235, 85 L.Ed. 132; Smith v. Magic City Kennel Club, 282 U.S. 784, 51 S.Ct. 291, 75 L.Ed. 707, and I.T.S. Co. v. Essex Rubber Co., 272 U.S. 429, 47 S.Ct. 136, 71 L.Ed. 335. In other words, in the present case, unlike the situation in the Boynton case, plaintiff is not relying upon something upon which the Examiner ruled he could not rely, and in which ruling plaintiff acquiesced, but on the contrary plaintiff relies upon what the Examiner has allowed him and merely says that the legal effect to be given to that allowance is not to be restricted to what the Examiner may have thought was the legal effect. The principle to be applied in such a situation is akin to that which is applicable to one who disclaims part of what he has claimed in a patent. His disclaimer does not have the effect of conceding that what was disclaimed' is, in fact, in the prior art. A patentee need not, at his peril, claim all that he might. See United Chromium, Inc., v. International Silver Co., 2 Cir., 60 F.2d 913, certiorari denied 288 U.S. 600, 53 S.Ct. 319, 77 L.Ed. 976. (b) Prior Art Disclosures Turning now to the prior art, defendants, in attacking the validity of the patent, rely upon five prior patents and two published articles, as follows: Patent No. 1,379,855 to Joseph Donner, issued May 31, 1921; patent No. 1,899,707 to Ralph H. McKee et al., issued February 28, 1933; patent No. 1,973,-130 to Harold G. Turley et al., issued September 11, 1934; French patent issued November 18, 1937, No. 824,804 to William Fletcher; and patent No. 2,123,214 to William B. Stoddard et al., issued July 12, 1938 ; “Effect of Sulfides on the Alkaline Hydrolysis of Skin and Hair” by Henry B. Merrill, published September, 1924, and “A Study of Keratin” by David R. Goddard et al., published May, 1934. Of the five patents just enumerated, we need devote little time to three of them, namely, the patents to Donner, to McKee et al., and to Stodd-ard et al., because the following brief analysis of each clearly indicates that none of them may properly be treated as anticipating any of the claims that are before us in the patent in suit. The Donner patent has been in litigation, and has been held valid as an invention over the prior art because it disclosed how a liquid depilatory could be converted into a stable cream depilatory through the use of certain colloid substances. See Donner v. Walgreen Co., D.C., 44 F.2d 637; Donner v. Sheer Pharmacal Corporation, 8 Cir., 64 F.2d 217, certiorari denied 290 U.S. 658, 54 S.Ct. 73, 78 L.Ed. 570. However, in Donner the depilating agent is a sulfide, not a mercaptan, as in the patent in suit. Nor is there any suggestion that a mercaptan be used. Sulfide depilatories having the inherent bad quality of producing a very objectionable odor, skin irritation and discoloration of jewelry, etc., it was to overcome these things that Evans and McDonough resorted to the use of mercaptans. In other words, they entered the field of organic chemicals and abandoned sulfides and other inorganic compounds whose usé had been commercially unsuccessful. In the McKee patent, the depilating agent is sodium stannite, a tin salt. The same is true with respect to the Stoddard patent. The use of mercaptans is not suggested in either McKee or Stoddard. Thus, although both these patents disclose a compound that is odorless, and although they have the same range of alkalinity as does the patent in suit, the difference with respect to the depilating agent employed is a, basic one. In short, both McKee and Stoddard may be considered as an improvement over Donner in that the suphur compound as prescribed by Donner had the very great drawback of (1) bad odor, and (2) dark color. These were overcome by McKee and Stoddarcl by the use of sodium stannite. McKee obtained his patent in 1933, Stoddard in 1938, and Stoddard represents an improvement over McKee in that Stoddard discloses a more stable stannite depilatory. Alkali stannites are very active substances, tending to decompose, which proves an obstacle to their use as depilatory agents because for this purpose it is necessary that the stannites remain undecomposed for long periods of time, in order that they may be distributed and sold to advantage in the retail trade. But Stoddard uses an alkali silicate as a stabilizer. It will thus be seen that such advance as was made in the art by McKee and Stoddard was still in an entirely different field from that of the patent in suit. Between the issuance of the patent to McKee and the patent to Stoddard, that is, in 1934 there was issued the patent to Turley, which represents the first depilatory patent disclosure in the same field which Evans and McDonough later entered, namely, the field of organic chemicals, through the use of mercaptans. It is this patent to Turley upon which defendants most strongly rely in their argument that the patent in suit is invalid for anticipation. Also, as we have already explained, it was the erroneous interpretation by the Patent Office Examiner of the upper pH limit in this patent which formed the basis for defendants’ argument that the plaintiff is restricted in the present suit to reliance upon that interpretation to prove invention by Evans and McDonough. The Turley patent is designated a “process of unhairing hides or skins.” There is no suggestion, express or implied, that the process relates to a cosmetic depilatory to be applied to the human skin. Furthermore, it is an immersion process. It may best be understood by quoting the following from the specifications of Turley: “This invention relates to a process of unhairing hides or skins by the use of mercaptans or those organic compounds containing or yielding a mercaptan or thiol group ( -SH) when employed with alkaline solutions such as now used for the removal of hair, fur or wool. “The object of our invention is to complete the process of, unhairing hides or skins in a shorter time than is ordinarily necessary and yet accomplish the unhairing process without creating or leaving any deleterious effect upon the hide or skin and with or without hair recovery depending upon the amount and nature of the above compounds.” On behalf of the plaintiff here it is asserted that Turley bears such a remote relation to Evans and McDonough that there is no ground for saying that Turley anticipates. In support of this position it is pointed out that in the one case it is the unhairing of dead, dried leather-making hides, and in the other, the cosmetic depilation of living, human skin. In unhairing, the hair is saved, or can be, and the epidermis is destroyed. In cosmetic depilation the hair is chemically severed at the very surface of the epidermis but the tenderest or most delicate skin is not even irritated or reddened. In unhairing, the entire flayed hide is wholly immersed in a liquid bath for several hours or even days. In cosmetic depilation, small areas of the living human skin are lightly coated during a period of from five to fifteen minutes with a fragrant cream which is wiped off as soon as the hair is severed. In unhairing, the liquid solution is always applied to and soaks through the derma from the flesh side, and usually through immersion is applied to both flesh and outer or hair sides simultaneously. In cosmetic depilation, the depilating compound is always applied on the hair side only and it never penetrates into or below the epidermal layer. In unhairing, the odor of such compounds as may be used is unimportant, as is also the optimum of alkalinity from the aspect of irritation of the skin. In a cosmetic depilatory, both pleasant odor and the optimum of alkalinity to avoid irritation are all-important. The aforegoing comparative analysis of the inherent distinctions between the objects sought to be attained by Turley on the one hand, and by Evans and McDonough on the other, are not subject to contradiction. Furthermore, it is to be noted that nowhere in either the specifications or claims of Turley is there any mention of pH limits for the obvious reason that, as we have already pointed out, non-irritation of the hide of a dead animal is not a factor to be considered. Indeed, if recovery of the hair is not desired, a high alkalinity is not objectionable. These considerations may well have influenced the Patent Office Examiner in his view that the compounds embraced by Turley were “extremely alkaline”. As a matter of fact, plaintiff’s testimony shows that, in testing out several of the formulas given by Turley, ■a pH as high as 12.95 was reached. In spite of these very definite differences underlying the two patents, defendants assert that the disclosure of Turley is, nevertheless, completely parallel in all of its material component parts with the disclosure in Evans and McDonough. Turley lists by name a large number of various types of mercaptans and includes thioglycollic acid. Also, in his specifications, Turley gives nineteen separate examples or formulas to be used, with a large number of different mercaptans. None of these illustrative formulas, however, specify the use of thioglycollic acid although, as just pointed out, it is listed in the specifications, and defendants introduced at the trial through their expert, Dr. Killian, tables showing the results that had been obtained by taking three of these illustrative formulas as given in Turley and substituting thioglycollic acid for the respective unhairing agents specified therein, namely, for butylcarbitol mercaptan, cysteine hydrochloride and benzyl mercaptan. These results, as Dr. Killian, the defendants’ chemist, testified, he compared with each one of the component parts of two of the narrowest claims in suit, namely, Nos. 2 and 13. Such comparison disclosed almost complete identity. In all six.instances a creamy, odorless preparation was produced which satisfactorily removed hair from the human arm without irritation within ten minutes. Also, in none of the three tests, where the substitution of thioglycollic acid was made, did the upper pH limit exceed 12.1. It reached that in one instance, was 11.9 in another, and 11.7 in the remaining instance. Dr. Killian further testified that similar comparative tests .made with two of the illustrative formulas, set forth in Turley, without making any change in the prescribed mercaptans, produced similar results, except that- in one instance, namely, that where cysteine hydrochloride was used, satisfactory, non-irritating depilation required from twenty to thirty minutes, instead of ten; and thqt in the other instance, where benzyl mercaptan was used, the resultant odor was that of a skunk. Plaintiff introduced no . evidence of a corresponding character. The most that plaintiff offered were certain specimens of the products which its analytical chemist testified resulted from following certain of the-specified formulas in Turley. These products were white and odorless, but very watery, with a large amount of sediment. From this, plaintiff would have us draw the conclusion that it is not possible to produce, by following Turley, a product such as that of Evans and McDonough, at least not one with such body and stability as is requisite if it is to be successful as a depilatory for the human skin. It is true, such testimony does indicate that a 'depilatory produced in conformity with the requirements of Turley is a more watery, less consistent product than that of Evans and Mc-Donough, — a slurry rather than a cream. Relying upon their testimony which we have just analyzed, defendants assert that there is no escape from applying to the Evans and McDonough patent the well established broad patent law doctrine that a patentee is entitled to every use to which his invention is susceptible, whether such use be known or unknown to him, and that, therefore, Turley must be treated as a clear anticipation of Evans and McDonough. As a broad, general definition of the law, the defendants have correctly stated it. See General Electric Co. v. Jewel Incandescent Lamp Co., 326 U.S. 242, 66 S.Ct. 81; Cuno Engineering Corporation v. Automatic Devices Corporation, 314 U. S. 84, 62 S.Ct. 37, 86 L.Ed. 58; Potts v. Creager, 155 U.S. 597, 15 S.Ct. 194, 39 L. Ed. 275; Ansonia Brass & . Copper Co. v. Electrical Supply Co., 144 U.S. 11, 12 S.Ct. 601, 36 L.Ed. 327; In re Thuau, 135 F. 2d 344, 30 C.C.P.A.(Patents) 979; Gilbert Spruance Co. v. Ellis-Foster Co., 3 Cir., 114 F.2d 771; In re Parker, Cust. & Pat. App., 107 F.2d 612; In re Sibley, 88 F.2d 960, 24 C.C.P.A.(Patents) 1143; Northam Warren Corporation v. D. F. Newfield Co., 2 Cir., 79 FBd 1005, affirming per curiam, D.C., 7 F.Supp. 773; General Electric Co. v. Hoskins Mfg., 7 Cir., 224 F. 464. The reason for .this rule is that a new use of an old thing, or an old process if unchanged, cannot be patentable because the statute allows patents only for a new “art, machine, manufacture, or composition of matter * * * ”, even though it may take as much or more inventive genius to discover the new use than the old one¡ R.S. 4886, 35 U.S.C.A. § 31. The statute does not permit patenting merely a new use but it must be a new art. The word “art” means “systematic application of knowledge or skill in effecting a desired result.” (Webster’s New International Dictionary). As was said in Ansonia Brass & Copper Co. v. Electrical Supply Co:, supra, 144 U.S. at page 18, 12 S.Ct. at page 604, 36 L.Ed. 327, “ * * * if an old device or process be put to a new use, which is not analogous to the old one, and the adaptation of such process to the new use is of such a character as to require the exercise of inventive skill to produce it, such new use will not be denied the merit of patentability.” Also, as was said in General Electric Co. v. Jewel Incandescent Lamp Co., supra, 326 U.S. at page 249, 66 S.Ct. at page 84: “It is not invention to perceive that the product which others had discovered had qualities they failed to detect.” And likewise in Cuno Engineering Corporation v. Automatic Devices Corporation, supra, 314 U.S. at page 91, 62 S.Ct. at page 41, 86 L.Ed. 58 it was said there must be revealed “the flash of creative genius not merely the skill of the calling.” Thus, if Turley actually disclosed the use of substituted mercaptans in an analogous art, then the most that Evans and Mc-Donough did was to select one of these substituted mercaptans which was best suited for their purpose of compounding a cosmetic depilatory, and this would not be invention because, while, from a group of chemical compounds taught by the prior art, the selection of one compound for use in a field closely related to the prior art field might require considerable skill and considerable laboratory experimentation, nevertheless, such selection would not rise to the dignity of invention within the meaning of the patent law. Therefore, claim no. 2 of Evans and McDonough would fall, and a fortiori so would the broader claims, nos. 11, 12 and 13. But we are satisfied that Turley does not teach the use of substituted mercaptans, but only the use of mercaptans generally. He nowhere refers to a class of “substituted mercaptans” as distinguished from “simple mercaptans”. Turley classifies mercaptans as (1) Aliphatic mercaptans, primary, secondary and tertiary, with one or more -SH groups; (2) Aliphatic mercaptans containing other groups in the molecule, such as, thioglycollic acid; (3) Ali-cyclic mercaptans; (4) Heterocyclic mercaptans; (5) Aralkyl mercaptans. He also states that his invention includes (6) Organic sulfides which give rise to a thiol group (— SH) by an internal rearrangement; (7) Organic sulfides in which the molecule has been so modified as to cause the liberation of a mercaptan in the presence of an alkali; (8) Compounds of those described in (1) to (6) with