5. Where there is a serious doubt left in the mind of this court, such doubt should be resolved in favor of the applicant for a patent; because, if his application be denied, he is not in a position to go into court and attempt to enforce a lawful monopoly. (Following Re Schraubstadter, 26 App. D. C. 331.)

6. A patentee is not obliged in his specifications to state ail the known equivalents of the materials used by him.

7. On an appeal from a decision of the Commissioner of Patents rejecting certain claims in an application for a patent for finish removers, it was held, reversing such decision, that the expression "a liquid finish solvent, ketonic derivative of a cyclic CH, hydrocarbon," used in the appealed claims, meant only such ingredients as were 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; and that, in view of the fact that no other phraseology could be employed to accord to appellant the protection to which he was entitled; that the substances embraced in the class claimed were generally capable of accomplishing the purpose of the invention; and that the claims must be construed in the light of the specification, and, if necessary, be limited by it, the claims should be allowed.

No. 703. 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 patent. Reversed.

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 Commissioners of Patents, refusing to grant certain claims made by appellant, Carleton Ellis, in an application for finish removers. The

Primary Examiner rejected these claims on the grounds, first, that they were devoid of invention; and, second, that to grant them would allow appellant to cover compositions of matter to which he was not entitled. On appeal, the Board of Examiners-in-Chief reversed the decision of the Primary Examiner as to the first ground of rejection, but affirmed it as to the second. This decision was affirmed by the Commissioner.

The appealed claims are eight in number, the following, however, being sufficient to illustrate the invention:

"7. The finish remover comprising composite finish solvent material, including a liquid, finish solvent, ketonic derivative of a cyclic CH2 hydrocarbon."

"11. The finish remover comprising composite finish solvent material, including a liquid, finish solvent, ketonic derivative of a cyclic CH2 hydrocarbon, and miscible solvent material of a generally penetrating and loosening character."

The invention is described by the Primary Examiner as follows: "The invention relates to paint removers. The wellknown paint removers contain solvents on the order of benzol, other solvents on the order of alcohol and stiffening material. The present invention uses in addition to the above well-known ingredients, cyclic CH2 hydrocarbons, as hexahydro benzol, or derivatives of cyclic hydrocarbons, as adipin ketone." The Patent Office has confined appellant to claims specifying adipin ketone as an ingredient. In his application, however, he has enumerated many other substances of the same chemical group, which possess the same properties as adipin ketone, and which may be used with equally satisfactory results. The specification states: "Many of the cyclic CH2 hydrocarbons and their derivatives are valuable as finish solvents in removers such as the cyclic paraffins, including cyclopentane or pentamethylene, vinyl trimethylene, suberane or cycloheptane, hexahydro benzenes or naphthenes, embracing hexahydrobenzol, hexahydro toluol and the like. Many immediate derivatives of these cyclic paraffins or cyclic hydrocarbons are also desirable finish solvents, such, for example, as acetyltrimethylene, diteramethylene ketone, adipin ketone (ketopentamethylene), methyl cyclopente

Opinion of the Court.

[37 App.. non, cyclopentane carboxylic acids, suberone, cyclohexanol, pimelin ketone, hexahydrometa toluic acid and similar carboxylic acids of the hydroaromatic group and other oxygenated or halogenated bodies thereof."

It was held by the Patent Office that to grant the claims: here under consideration will extend the scope of appellant's invention beyond that to which he is entitled, and will permit him to stand in the path of subsequent inventors in the same. art. It was also held that to determine which of the cyclic CH2 hydrocarbons not mentioned in the application are finish solvents will require experiment. But the injustice to which this ruling will lead is manifest. Counsel for appellant stated at bar, and it was not controverted, that no phraseology other than that of the claims here in issue could be employed in broadly defining the invention, and that, if these claims be not allowed, appellant will be limited to a patent covering the use of adipin ketone only. This would furnish him little or no protection in the practice of his invention. A competitor could use with impunity any of the numerous equivalents specified by appellant, and not come within the scope of the patented claims.

*

The object of the patent laws is to secure to the inventor the full rewards of his invention. He is not limited to the use of one specific substance, but his patent covers all known equivalents. In Robinson on Patents, secs. 257 and 258, it is said: "As the substitution of equivalents works no variation in the substance of an invention, so all equivalents, whether actually known to the inventor or not, are covered by his patent. * * The doctrine of equivalents applies alike to all classes of inventions, and to all inventions of whatever class. Equivalentsin an art or process are such acts as, in accordance with preceding rules, are interchangeable with those which the inventor has himself employed. * * * In compositions of matter, substances which, at the granting of the patent, were known as capable of serving the same purpose in the composition as the ingredients actually employed become thereby their chemical equivalents." But the specification and claims must be

broad enough to cover them. Read Holliday & Sons v. SchulzeBerge, 78 Fed. 493.

Neither do we think that the allowance of the claims in issue will have the effect attributed by the Patent Office. The claims of a patent must be construed in the light of its specifications and drawings, and may be limited, but not enlarged, by them. Continental Paper Bag Co. v. Eastern Paper Bag Co. 210 U. S. 405, 52 L. ed. 1122, 28 Sup. Ct. Rep. 748. Here appellant has specified numerous substances which he declares are not only finish solvents themselves, but are similar to others in the class which he seeks to cover by the appealed claims. They are sufficient to convey to one skilled in the art the nature of the chemicals which will accomplish the desired result. The range of equivalents depends upon the nature and extent of the invention. If the invention be broad and primary, the range of equivalents will be likewise broad; if the invention be but an improvement over the prior art, the range of equivalents will be correspondingly restricted. Ibid.

But the equivalent, the use of which is sought to be embraced in the patent, must be one known, or which could have been known without the exercise of inventive skill, at the time of the patent. In the case of American Sulphite Pulp Co. v. Howland Falls Pulp Co. 25 C. C. A. 500, 50 U. S. App. 52, 80 Fed. 395, the following was quoted with approval from Read Holliday & Sons v. Schulze-Berge, supra: "I think the law must be that where the new ingredient is such as would have been known to or employed by the ordinary skilled, practical chemist, or is such as would naturally have been developed in the growth of the art, and the substitution thereof involves no alteration or new operation or result, it is covered by the patent, provided the specifications and claims are sufficiently broad to include it." Robinson, Patents, sec. 257; Walker, Patents, sec. 354. And in Standard Paint Co. v. Bird, 175 Fed. 346, the same rule was laid down, as follows: "To infringe a patent of this description, the alleged infringer must use the ingredients claimed to be those used in the process, or used to form the product, or a 'well-known' equivalent therefor.

It is not sufficient that tests or experiments have shown that some substance not claimed, and, at the time the patent was applied for and granted, not known, to be an equivalent, had proved just as good or just as efficient in the combination as a substitute for the ingredient claimed. Gill v. Wells, 22 Wall., 1, 22 L. ed. 699; Seymour v. Osborne, 11 Wall. 555, 20 L. ed. 42; Brown v. Stilwell & B. Mfg. Co. 6 C. C. A. 528, 6 U. S. App. 427, 16 U. S. App. 234, 57 Fed. 731; Rowell v. Lind say, 113 U. S. 97, 28 L. ed. 906, 5 Sup. Ct. Rep. 507."

The Patent Office relies upon the cases of Re Incandescent Lamp Patent, 159 U. S. 465, 40 L. ed. 221, 16 Sup. Ct. Rep. 75, and Matheson v. Campbell, 24 C. C. A. 384, 45 U. S. App. 473, 557, 78 Fed. 910. The former case is easily distinguished from the case at bar. There, the plaintiffs had discovered that carbonized paper could be used as the filament for incandescent lamps. They did not, however, confine themselves to such material, but also made claims to filaments of carbonized fibrous and textile material. It appeared that an examination of over six thousand vegetable growths showed that none of them could be used for that purpose. It was only after experiments lasting several months that the defendant discovered a substitute in a certain kind of bamboo. At the time of plaintiffs' patent there were no known equivalents of their carbonized paper filament, and apparently none could have been ascertained without invention. The court, in holding them limited to a claim for the material they had described, used the following language: "If the patentees had discovered in fibrous and textile substances a quality common to them all, or to them generally, as distinguishing them from other materials, such as minerals, etc., and such quality or characteristic adapted them peculiarly to incandescent conductors, such claim might not be too broad." The case at bar, being an ex parte proceeding for the allowance of certain claims, contains no testimony to show whether or not substances of the class called for in appellant's claims are generally capable of dissolving finish. But as appellant has specified a large number of substances containing the common quality which fits them for use in his in