In an action for the infringement of a patent right for producing a yellow color for painting in oil or water, and making white lead, and separating the mineral alkali from common salt, it appeared that the specification commenced as follows: "Take any quantity of lead, and calcine it, or minium, or red lead, litharge lead, ash or any calx, or preparation of lead, fit for the purpose." At the trial, it was objected to the specification that, after directing that the lead should be calcined, it stated that minium might be used, which would not answer the purpose. Neither was it said that the minium should be calcined or fused; but if minium had any reference to the preceding words, then it was to be calcined, which would not produce the effect, fusion being necessary. Buller, J. said, that "it was not pretended by any of the plaintiff's witnesses that he ever made use of minium. And it was proved by the defendant's witnesses, that from the specification, they should be led to use minium, because minium is lead already calcined, which is what the specification directs in the first instance. But minium will not answer the purpose. Then as to fusion, it is said, that the public are directed, by the words of the specification, to continue the heat till the effect is produced; which must necessarily lead to fusion, though fusion is not expressly mentioned. But that is no answer to the objection; for the specification should have shown by what degree of heat the effect

was to be produced. Now it does not mention fusion, and, as one of the witnesses said, in order to produce the effect, you must go out of the patent; for fusion is beyond calcination, and in some sense contrary to it; and by mentioning calcination, it should seem that fusion was to be avoided. He was accordingly of opinion that on this ground the patent was void." Ashurst J. "The first objection to the specification is, that the public are directed to take any quantity of lead, and calcine it, or minium, or red lead;' from whence it is inferred that calcining is only to be applied to lead; I confess, if the objection had rested here, I should have entertained some doubt."72

The same specification proceeded as follows: To any given quantity of the above-mentioned materials, add half the weight of sea salt, with a sufficient quantity of water to dissolve it, or rock salt, or sal gem, or fossil salt, or any marine salt, or salt water proper for the purpose. It was objected that fossil salt was improperly mentioned. For fossil salt is a generic term, including all mineral salts, only one of which, sal gem, would answer the purpose; because that alone has marine acid. Ashurst J. understand that sal gem is the only one which can be applied to this purpose; so that throwing in

72 Turner v. Winter, 1 T. R. 602.

fossil salt can only be calculated to raise doubts and mislead the public. That word could not have been added with any good view; it must produce many unnecessary experiments; therefore, in that respect, the specification is not so accurate as it should have been." The patent was held to be void.73

In the same case, Buller, J. said, that "if the patentee could only make the color with two or three of the ingredients specified, and he has inserted others in the specification which will not answer the purpose, that will avoid the patent. If the patentee makes the article for which the patent is granted, with cheaper materials than those which he has enumerated in the specification, although the latter will answer the purpose equally well, the patent is void, because he does not put the public in possession of his invention, or enable them to derive the same benefit from it which he himself does."""4

So Mr. Chief Justice Gibbs says, "A person who applies for a patent, and proposes a mode of carrying on the invention in the most beneficial manner, must disclose the means of producing it in equal perfection, and with as little expense and labor as it costs the inventor himself. The price that he pays for his patent is, that he will enable the public, at the expiration of his privilege, to make it in the same

73 Turner v. Winter, 1 T. R. 602, 14 Turner v. Winter, 1 T. R. 607.

way, and with the same advantages. If any thing which gives an advantageous operation to the thing invented, be concealed, the specification is void."75

A patent was granted for a new mode of making verdigris. The patentee was accustomed, during the process of the manufacture, clandestinely to introduce aqua fortis into the boiler, by means of which a more rapid solution of the copper was produced. This was not stated in the specification. Gibbs C. J. "Although the specification should enable a person to make verdigris substantially as good without aqua fortis as with it; still, inasmuch as it would be made with more labor by the omission of aqua fortis, it is a prejudicial concealment, and a breach of the terms which the patentee makes with the public. If it is proved that aqua fortis was used by the inventor as an ingredient, the patent is void."76

A patent was obtained for a new method of drying and preparing malt. It was objected that the patent was void, because it appeared from the specification, that it was merely a method of giving to malt, previously prepared, the qualities of being soluble in water and coloring the liquor in which it should be dissolved, which was accomplished by the application of a high degree of heat. Abbott C. J. "It

75 Wood v. Zimmer, Holt's N. P. C. 58. 76 Wood v. Zimmer, Holt's N. P. C. 58

was argued that the term, malt, is applied to the grain as soon as it has germinated by the effect of moisture, and before it has been dried; that malt in that state might be taken and used for the objects of the invention; and that, as these were to be accomplished by heat, it was an invention for drying malt. But if this were so, then the specification would be defective in not informing the reader, that the malt to be used for the intended object might or ought to be taken in that state, and in leaving him to discover by experiment whether it should be taken in that state, or after drying, which, according to the most common use of the word malt, he might very reasonably suppose.

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On the subject of the patentee's describing the best way of practising the art or making the article patented, the English jurisprudence presents one rule which is not applicable in ours. As the inventor is, in England, allowed a certain time after the grant of the patent to enrol his specification, and as during that time he may make new discoveries and improvements, he is required to describe in his specification, not merely the best method known to him at the time of taking out the patent, but he must include also all his subsequent discoveries and improvements, down to the time of specifying."

In

77 King v. Wheeler, 2 Barn. & Ald. 353.

78 Crossley v. Beverly, 9 Barn. & Cress. 63. In stating this doc