vention, in the absence of evidence to the contrary, we believe that the doubt should be resolved in his favor. "Where there is a serious doubt left in the mind of this court, we believe that that doubt should be resolved in favor of the one seeking a patent; for, if his claim be denied, he has nothing with which he can go into court and attempt to enforce a lawful monopoly." Re Schraubstadter, 26 App. D. C. 331.

The case of Matheson v. Campbell, supra, might also be distinguished on the ground that the patentee had "himself experimented only with three of four bodies out of a group of hundreds." But if not, it has not been followed by the later decisions. In Fullerton Walnut Growers' Asso. v. AndersonBarn-Grover Mfg. Co. 92 C. C. A. 295, 166 Fed. 443, a case closely analogous to the one at bar, the patent before the court was for a process for bleaching nuts, in which a weak acid was specified as an ingredient. In discussing a contention similar to that made by the Patent Office here, the court said: "But it is said that the term 'weak acid' is indefinite, and that the appellant which used diluted sulphuric acid, was not precluded from such use, since sulphuric acid is not a weak acid, and no standard of acidity is fixed by the term 'weak acid.' But by specifically referring to the use of vinegar, the patentee has made known the standard of acidity of the acid which will operate successfully with the solution. He declares in his specifications that he has found that, while many acids might produce the result of liberating the gas, a safe acid for the purpose is acetic acid or vinegar. In his claim he confines himself to no specific acid. The appellant has found that by the use of diluted sulphuric acid the bleaching process can be as effectually accomplished as by the use of vinegar. But it does not thereby avoid infringement. It uses a weak acid within the terms of the claims. *Obviously he was

*

*

not required to experiment with all kinds of acids, and to state in his specifications what acids would and what would not be suitable for the purpose, and we think it does not extend the patent beyond its proper scope to say that it covers the use of any acid which, by chemical reaction, will release the chlorin

Vol. XXXVII.-14.

in the bleaching solution. A strong acid would cause a violent and sudden evolution of chlorin, which would almost instantaneously be dissipated. A weak acid releases the chlorin gradually and continuously. There doubtless are acids known to chemistry which will not accomplish the reaction incident to the release of the chlorin, but the acids commonly known, such as acetic, sulphuric, muriatic, oxalic, and nitric acids, when diluted to the acidity of vinegar, may, it is shown, be successfully used in the process."

In the case of Welsbach Light Co. v. Sunlight Incandescent Gas Lamp Co. 87 Fed. 221, where the claim was drawn to cover "paraffin, or other suitable material, substantially as set forth," the court said: "While collodion is not chemically an equivalent of a hydrocarbon resin gum, and is not paraffin or shellac, it performs the same functions, in the same manner, and with the same result. A patentee is not obliged, in his specification, to state all the known equivalents of the materials used by him. It is the patent as finally issued which the court is to construe, and upon which the patentee must stand. In this case the patentees have claimed 'paraffin, or other suitable material, substantially as set forth.' They have set forth that 'other materials may be employed, as long as they set hard at ordinary temperatures, and burn away without mechanical destruction to the mantle.' The defendant uses a suitable material, known at the date of the invention to have all these properties and characteristics, and has thereby appropriated complainant's product."

And in the case of American Sulphite Pulp Co. v. Howland Falls Pulp Co. supra, where a patent claiming cement as a lining for digesters was in issue, the court said: "And we think, upon principle and authority, that Russell, having discovered that cement material generally possesses the qualities required for his conception of a homogeneous digester lining, should not be limited to such materials in the class of cementitious mixtures as he had chemically and commercially isolated as individuals, but that his claims and description should be construed as including all cementitious mixtures which ordinary

skilled practical chemists might be expected to find as answering the requirements of the described conditions, or such as would naturally develop in the growth of the art without invention."

We have cited numerous cases and quoted from the decisions at great length, for the reason that the case before us in a highly technical one. From a review of the authorities, and the application of the rule so generally announced, we think it is apparent that the expression, "a liquid, finish solvent, ketonic derivative of a cyclic CH2 hydrocarbon," used in the appealed claims, means only such ingredients as are the known equivalents of those specified in appellant's application, or which could be ascertained to be such by those skilled in the art, without the exercise of invention. Whether the range of equivalents covered by these claims be broad or narrow depends upon the prior art, and is a question of construction. In view of all the facts of the case, the fact that no other phraseology can be employed to accord to appellant the protection to which he is entitled; the fact that, from the record, there is a fair presumption that the substances embraced in the class claimed are generally capable of accomplishing the purposes of the invention; and the further fact that the claims must be construed in the light of the specification, and, if necessary, be limited by it, we are of opinion that the claims here under consideration should be allowed.

The decision of the Commissioner of Patents is reversed, and the clerk is directed to certify these proceedings as by law required. Reversed.

IN RE DOSSELMAN.

PATENTS; CLAIMS AND SPECIFICATIONS; EQUIVALENTS.

Where an application for a patent for a finish remover covered a composition having acetone as one of its ingredients, without referring to any

Opinion of the Court.

[37 App. equivalent for it, and five years after the filing of the application, during which time the finish-removing art had been extensively devel oped, the applicants presented claims substituting ketones generally for acetone, it was held that such claims were properly rejected by the Commissioner, as beyond the original disclosures of the appli cants. (Distinguishing Re Ellis, ante, 203.)

No. 704. Patent Appeals. Submitted March 14, 1911. Decided May 1, 1911.

HEARING on an appeal from a decision of the Commissioner of Patents, rejecting certain claims in an application for a patent. Affirmed.

The facts are stated in the opinion.

Mr. Melville Church and Mr. Harry L. Duncan for the appellant.

Mr. Robert F. Whitehead for the Commissioner of Patents.

Mr. Justice VAN ORSDEL delivered the opinion of the Court:

This is an appeal from the decision of the Commissioner of Patents, refusing to grant certain claims to appellants, Gustav Dosselman and Percy Neymann, in an application for patent for a composition for removing surface finishes. The following are illustrative of the claims involved in this appeal:

"9. The substantially fluent finish remover comprising substantially equal parts of ketonic finish-softening material and other miscible finish-softening material and incorporated evaporation-retarding material, including paraffin.'

"15. The substantially fluent finish remover substantially neutral to wood, comprising composite finish-softening material, including aromatic finish-softening material and incorporated colloidal thickening material."

"23. The substantially fluent finish remover substantially neutral to wood, consisting substantially of organic finish-softening material and incorporated substantially solid thickening

material, thickening the remover to substantially semi-paste consistency."

The invention is described by the Board of Examiners-inChief as follows: "The original specification of this application covers a composition for removing paint or varnish, consisting of benzol, acetone, and paraffin. It further specifies that instead of benzol, other coal-tar products and petroleum products, such as benzene or alcohol may be substituted, and that instead of paraffin any wax mineral such as hydrocarbon, vegetable such as carnauba, or animal such as fatty acids or beeswax. When the composition is to be made into a semi-paste, coresine wax is added. No equivalent for acetone as an ingredient in the paint remover is referred to."

The claims under consideration were rejected by the tribunals of the Patent Office on the ground that by the use of the terms "ketonic finish-softening material," "aromatic finishsoftening material," and similar expressions, appellants had attempted to broaden their claims beyond the scope of their original disclosure, and to cover an invention which had not been made by them prior to the filing of their application. The law relating to this question was discussed at length in the case of Re Ellis, ante, 203, in which claims containing a somewhat similar term were allowed. In that case the applicant had enumerated a large number of ingredients which could be used interchangeably in practising the invention, so that the court felt justified, in the absence of evidence to the contrary, in assuming that the substances embraced within the class called for by the claims were generally capable of accomplishing the desired result. Here, however, the only ketone disclosed in the application is acetone. This seems to have been the only substance appellants had in mind for serving the purpose for which it is used. They confined themselves to this until five years after the filing of their application, during which time the finish-removing art had been extensively developed, when they presented the present claims. There is nothing in their application to warrant the presumption that they had discovered that ketones generally could be used as an ingredient in their