Every patent for a product or composition of matter must identify it so that it can be recognized aside from the description of the process for making it, or else nothing can be held to infringe the patent which is not made by that process. (Cochrane v. Badische Anilin, etc., C. D., 1884, 230; 27 O. G., 813; 111 U. S., 293.)

Now, there are many tests that may be applied to two bodies which are being compared in order to determine whether they are or are not identical. The number of those tests may be multiplied indefinitely, for the skill, the experience, the scientific ingenuity of the chemist will ever devise new ones in the future, as they have the old ones in the past. Some of these tests will be of great significance, some almost crucial; others will be of but minor importance. Their relative value no doubt may change as science goes sweeping on from point to point; but it must be sound law, as it is reasonable common sense, to hold that the tests of prime importance in a suit for infringement are those which the patent itself prescribes. The inventor certainly may be assumed to know what it is that he has invented. If any one is able to describe the product of his inventive skill, it is himself. He surely knows the earmarks of the thing he seeks to patent, and when out of the multitudinous qualities which his product may exhibit under vary. ing conditions and in different relations he has selected and set forth in his patent a chosen few, surely these should be accepted as the distinguishing earmarks, the characteristic stigmata, of the product. his patent is to cover. It may be that, after it is found that the body under investigation responds to all the tests of a patent, science may yet be able to demonstrate by other tests that nevertheless it is not the new product therein patented; that the patentee had selected identifying tests broader than he was entitled to and which would cover products not within the range of his discovery; but when the body under inves tigation fails to respond to the specific tests the patentee has himself selected, he certainly cannot fairly insist that it is identical with his product.

In framing the patent in suit care was taken to avoid the difficulty pointed out in Cochrane v. Radische Anilin, supra. Certain identifying tests were set forth, so that the inventors might be able to contend that a chemical compound which responded to them all was, prima facie at least, an infringement of their patent. The tests of the patents

are:

First. The dyestuff is a black paste or in solid form, and though the patent does not say so, this test would be fairly responded to if the black solid had been mechanically transformed into a black powder. Second. It produces on the fiber, in an acidulated bath, dark-blue shades.

Third. It is very soluble in water.

Fourth. It is insoluble in spirit.

Fifth. It dissolves in strong sulfuric acid with green color.

Sixth. Reducing agents destroy the color-forming alpha-naphthylamin besides other products.

The dyestuff as to which it is to be determined whether or not it infringes, is the dyestuff sold by defendant, of which a can was by stipulation put in evidence as "Complainant's Exhibit Defendant's Color." There is no evidence at all in the case by what process this dyestuff was made. Complainant therefore undertook to prove infringement by the application of "tests." His expert testified that he had applied thirty-four (34) tests, and that of those tests five (5) are named in the patent. We have carefuly examined his enumeration of the tests he applied and fail to find therein more than four (4) of the tests of the patent-viz., the third, fourth, fifth, and second. In applying the fourth test he used both methylic alcohol, in which it was soluble, and ethylic alcohol, in which it was not; but he evidently does not mean to imply that these are to be taken as two tests under the patent, for if the various double and triple tests of his enumeration are to be thus split up, the list will number more than thirty-four. The evidence supports the conclusion of the Circuit Court that the words "insoluble in spirit" refer to ethylic alcohol, not to methylic alcohol. To the four tests of the patent which complainant's expert applied the defendant's dyestuff responded.

The testimony as to the first test of the patent is not very satisfac tory; but in view of the sense in which the word "black" appears to be used in this art, we are not prepared to say that defendant's color failed to respond fairly to this test.

The sixth test, above quoted from the patent, brings up a question of construction. It reads:

Reducing agents destroy the color-forming alpha-naphthylamine besides other products.

Even without any evidence it is apparent that the sentence is awkwardly expressed. It seems to imply that the black paste or solid consists of alpha-naphthylamin, which forms the color, and of other products, and that reducing agents destroy them all. The proof shows conclusively-all the experts agreeing-that there is no alpha-naphthylamin in the black paste or solid. The alpha-naphthylamin perished long before the ultimate black paste of the patent appeared. Complainant's expert suggests that the sentence means that

by reducing agents alpha-naphthylamin which was used to form the color of the patent in suit, and therefore in the patent is named the color forming alpha-naphthylamin, is destroyed.

But this is not materially helpful, for he says that reducing agents would not change alpha-naphthylamin at all, and he most certainly concedes that in the ultimate product of the patent alpha-napthylamin does not exist as such. The sum of his testimony is that the reducing agents are to be applied to the color. In the light of the testimony the sentence as it stands is, if not meaningless, at least ambiguous. It is apparent that the awkwardness of the sentence arises from the nse of the hyphen between "color" and "forming." If that were eliminated, all concede that the plain meaning of the sentence would

be that reducing agents would destroy the color and alpha-naphthylamin would be formed. And the same result would follow if the hyphen were made a little longer, so as to become a printer's dash. It is not necessary, however, to theorize upon this point or to guess at the meaning of the sentence. It is demonstrable by evidence well recognized as competent in patent causes that the presence of the hyphen is due to a printer's error.

The file-wrapper shows that as to tests the original specification read as follows:

These new dyestuffs produce on wool and silk in an acidulated bath violet to darkblue shades. They are very soluble in water, insoluble in spirits and dissolve in strong sulphuric acid with green color. They are destroyed by reducing agents, forming alpha-napthylenediamin besides other products.

Subsequently this part of the specification was amended so as to read as follows:

Naphthol-black produces on the fiber in an acidulated bath dark-blue shades. It is very soluble in water, insoluble in spirit and dissolves in strong sulphuric acid with green color. Reducing agents destroy the color-forming alpha-naphthylamine besides other products.

And in this form it was allowed by the Patent Office. That the hyphen was inserted in the printed copies issued by the Office through a printer's blunder is manifest. It is apparent, then, that the inventors prescribed as one of the tests which would disclose the identity of any body with their product the action of reducing agents thereon. This action must be such as to destroy the color and form certain products. The characteristic product of those thus formed, the one which they selected as determinative under this test, they originally declared to be alpha-naphthylenediamin. Subsequently and before the patent issued they changed that declaration to alpha-naphthylamin. There is no evidence that one skilled in the art would know when he saw alphanaphthylamin named as the identifying product that it was a misnomer for alpha-naphthylenediamin. We know no reason why they should not be held to the selection they thus declared to the public as one of the characteristic tests of their product. If this were a blunder of an ignorant solicitor, they had ample opportunity to correct it by reissue; but, having allowed it to stand in their patent, they must be held to their declaration that reducing agents will produce this result.

It has been suggested that since the evidence shows that alphanaphthylamin would not be formed out of the product of the patent by reducing agents, and that persons skilled in the art would know that fact, the entire test may be rejected as nonsensical surplusage. But there must be some limit to a court's functions in rewriting patents. Assuming that all the imperfections in this patent were due to an ignorant solicitor remote from his clients-aud it may be noted that there is no evidence of this-it does not follow that all should be disregarded. We held as to the error and omission of paragraph 4 that the omis sion was really supplied elsewhere in the patent; that the error was

harmless, since the skilled workman would himself substitute nitrite for nitrate, and that, although the error must stand in the patent where the patentee's careless solicitor had placed it, we would not infer from its presence that it was due to a fraudulent design to mislead, formed and carried out by the patentees. But here there has been an identifying test put into the patent by the solicitor; the patentee accepts such patent and applies for no reissue, alleging no mistake, and the court is asked to strike out the test altogether as ridiculous surplusage. In the absence of any authority for such action we are unwilling to establish the precedent. By what their solicitors do patentees should abide. If they are dissatisfied with the Letters Patent their solicitors obtain, they may in proper cases apply for a reissue; but when they accept their original patents without objection, they must be assumed to have assented to such changes as were made by their solicitors in specification or claim while their application was on its way through the Patent Office.

When defendant's coloring matter is treated with reducing agents, it is destroyed, but no alpha-naphthylamin is formed. We have, then, a case where the inventor has prescribed six tests in his patent, and an alleged infringing body responds to five of them, but fails to respond to the sixth. Manifestly it is not absolutely identical with the product of the patent, as the inventor has defined that product by distin guishing characteristics. It may be that the variance results from some immaterial change in the process-from the use of starting material which is within the fair range of equivalents-but having failed to prove identity by the prescribed tests, the burden is on the holder of the patent to show that the variances in process are immaterial or the starting materials equivalents of those of the patent. There being no such proof here, the complainant must stand or fall by the results of the tests of the patent, and since the defendant's color does not respond to these, it cannot be held to be an infringement.

The conclusion thus reached renders it unnecessary to discuss the other points raised in the case.

The decree of the Circuit Court is reversed, with costs, and cause remanded, with instructions to dismiss the bill.

Court of Appeals of the District of Columbia. į

HUNT et al. v. MCCASLIN.

Decided April 6, 1897.

79 O. G., 861.

1. INTERFERENCE-APPLICANT AND PATENTEE-BURDEN OF PROOF.

The burden of proof is upon the party who is the last to file his application in the Office, and this status of the parties is not changed by the fact that the junior applicant may have obtained a patent.

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2. SAME CONCEPTION-DILIGENCE IN FILING APPLICATION.

Long delay in filing an application for a patent after alleged conception of the invention casts a doubt upon the allegation of conception, but it may be shown by the circumstances to be not inconsistent with inventorship.

3. SAME-CONtract BETWEEN THE PARTIES-QUESTION of Invention.

A contract between the parties whereby they agreed to transfer all inventions made by them to a certain company can have no bearing on the question as to which of these parties is the inventor of a certain machine, but bears only on the question of ownership of the invention.

Mr. Wm. H. Doolittle for the appellants.

Mr. Thos. Ewing, Jr., and Mr. V. M. Dorsey for the appellee.

MORRIS, J.:

This is an appeal from the decision of the Commissioner of Patents in an interference proceeding instituted in the Patent Office between the appellant, Charles W. Hunt, and the appellee, George W. McCaslin, with reference to an invention in the matter of eudless-chain conveyors, which has been defined in the Patent Office in four different counts or statements, as follows:

1. In an endless-chain conveyor, the combination, with the track, track-wheels, and endless chains, of gravity-buckets pivoted to the chains and provided with lips at the front and back ends that lap one over the other, and means for tilting the buckets in succession for discharging the contents, and additional means for tilting the buckets on their pivots and turning them over for the lips to lap in the position for being refilled, substantially as set forth.

2. An endless-chain conveyor having a chain, with gravity-buckets suspended pivotally therein and provided each with a lip at each end, the lips on the adjacent buckets overlapping as set forth, and means situated at the point where the buckets approach the descending track, for tilting the buckets, the construction and arrangement of said means being such that the overlapping of the lips thereon will be changed, substantially as specified.

3. In an endless-chain conveyor, the combination with the track, track-wheels and endless chain, of the gravity-buckets suspended at intervals in the chain and provided with overlapping lips as described, and means substantially as described for preventing the collision of the loaded buckets when they pass from the lower track to the ascending track, substantially as set forth.

4. In a conveyor, the combination with an endless track, the track-wheels thereon for carrying the chain, and the endless chain, of gravity-buckets, pivotally sus pended at equal intervals in the chain, and each provided with dumping-lugs, and lips, one at each end, the lip on the rear end of a bucket overlapping the lip on the front end of the following bucket when the buckets are moving along a horizontal track, and means substantially as described for tilting the buckets, and means for shifting the lap of said lips when the buckets move on to the descending tracks, substantially as set forth.

For this invention a patent was issued to the appellee, George W. McCaslin, on August 22, 1893, No. 503,870, in pursuance of an application filed by him on April 8, 1893. But there was pending in the Office at the time the application of the appellant, Hunt, filed on September 10, 1892, for a patent substantially for the same invention, which for some reason was delayed in its progress through the Patent Office, so that the propriety for a declaration of interference between him and McCaslin did