sure upon one of its particles is propagated throughout the mass, and a slight blow or jar detonates the mass. This property of explosion by a slight blow producing pressure renders the handling of nitroglycerine exceedingly dangerous. Nobel discovered that when the liquid nitroglycerine is compounded mechanically with a fossil earth in a powdery condition this property is neutralized; the explanation of change of effect or mode of operation appearing to be that whereas in the liquid nitroglycerine its particles are in such intimate relationship as to be in concussive contact, they are separated when the nitroglycerine is mechanically compounded with a powdered solid substance and concussive contact is prevented. The name of Dynamite was given to this new compound, and it was a new and very useful invention, for while it possesses the valuable properties of nitroglycerine as an intensely active explosive, it is free of the risk of explosion by a slight jar or blow incurred in handling and transporting it.

Dynamite is a mechanical composition of liquid nitroglycerine and a powdered solid, and after Nobel's dis covery new dynamites were devised in which the powdered fossil earth used by Nobel was replaced by other solid substances in the condition of powder. In one of these new dynamites the solid ingredients employed were the same as those of gunpowder; that is to say, the producer of the new dynamite compounded nitroglycerine with meal powder instead of with fossil earth powder. Was this change a mere substitution of one material for another, or was it more? When the original dynamite was exploded the solid matter with which the nitroglycerine was compounded was incombustible and inert to produce gases. Hence the volume of gases produced was that

incident to the explosion of the nitroglycerine of the compound alone. With the new dynamite the powdery solid matter was combustible, and when the compound was exploded the gas produced was the sum of those evolved by the nitroglycerine and of those evolved by the meal powder, and this was a new mode of operation. In the respect that the meal powder in the new compound neutralized the dangerous property of unmixed nitroglycerine for handling, the meal powder was the equivalent of the fossil earth powder, and the new compound clearly embodied Nobel's invention; and if this had been all that the meal powder did, the change from fossil earth powder to meal powder (each being an old pulverulent material) would have been a mere substitu-. tion of one well known pulverulent material for another; but in the respect that the change imparted to the new compound the new mode of operation, the change was not a mere substitution of one ingredient for another, but produced a substantially new composition of matter, analagous to a new combination of old mechanical devices. Hence in the case of such a change in a mechanical composition the product is an invention which should be patentable; and in such a case the question whether invention exists is not a matter of mere opinion but is capable of proof by evidence.

§ 67. Invention by Substituting One Ingredient for Another in a Chemical Composition of Matter.

The same principles hold good in cases of chemical compositions. Thus, common salt, chemically known as chloride of sodium, is a chemical compound of sodium and chlorine, one atom of each. The atom of sodium may be replaced by an atom of calcium, in which case the chemical compound is known as the chloride of cal

cium. But the properties or qualities of the two chlorides are wholly dissimilar in several important respects, and consequently if some person had produced the chloride of calcium subsequent to the existence of the chloride of sodium, the change would not have been a mere substitution of one known ingredient (calcium) for another (sodium) in an old composition of matter, but would have been an invention.

§ 68. Invention by Change of Proportions of the Ingredients of a Composition of Matter.

There is also the question with reference to a composition of matter, whether a change of the proportions in which the same ingredients are compounded does or does not constitute an invention. We have an instance of such a change in the case (previously referred to in § 9) of the soft vulcanized rubber, or composition of rubber and sulphur invented by Charles Goodyear, and the hard vulcanized compound of rubber and sulphur (Vulcanite) subsequently invented by Nelson Goodyear. In the latter case the change in the proportions of the sulphur to the rubber produced a compound (vulcanite or hard rubber) having qualities in many respects different from those of the older soft rubber compound of Charles Goodyear. Hence the change was not a mere change of proportions, but was a substantial one amounting to invention, and it was recognized as such by the court.

PATENTABLE DESIGNS.

§ 69. The Statute of 1842.

By the Patent Act of 1842, a new class of articles commonly known as designs were made proper subjects

of patents. The section of that Act relating to this subject is in the following words:

"That any citizen or citizens, or alien or aliens having resided one year in the United States and taken the oath of his or their intention to become a citizen or citizens, who by his, her, or their own industry, genius, efforts, and expense, may have invented or produced any new and original design for a manufacture, whether of metal or other material or materials, or any new and original design for the printing of woolen, silk, cotton, or other fabrics, or any new and original design for a bust, statue, or bas relief or composition in alto or basso relievo, or any new and original impression or ornament, or to be placed on any article of manufacture, the same being formed in marble or other material, or any new and useful pattern or print, or picture to be either worked into or worked on, or printed, or painted, or cast, or otherwise fixed on any article of manufacture, or any new and original shape or configuration of any article of manufacture not known or used by others before his, her, or their invention or production thereof, and prior to the time of his, her, or their application for a patent therefor, and who shall desire to obtain an exclusive property or right therein to make, use, and sell and vend the same or copies of the same, to others, by them to be made, used, and sold, may make application in writing to the Commissioner of Patents expressing such desire, and the commissioner, on due proceedings had, may grant a patent therefor, as in the case now of application for a patent."

§ 70. Dictum of the United States Supreme Court. In the leading decision on this subject (Gorham Co. v. White, 81 U. S. 14 Wall. 525, 20 L. ed. 736) by the

United States Supreme Court the court made the following dictum:

"The acts of Congress which authorize the grant of patents for designs were plainly intended to give encouragement to the decorative arts. They contemplate not so much utility as appearance, and that, not an abstract impression or picture, but an aspect given to those objects mentioned in the acts. It is a new and original design for a manufacture, whether of metal or other material; a new and original design for a bust, statue, bas relief, or composition in alto or basso relievo; a new or original impression or ornament to be placed on any article of manufacture; a new and original design for the printing of woolen, silk, cotton or other fabrics, a new and useful pattern, print, or picture, to be either worked into, or on, any article of manufacture; or a new and original shape or configuration of any article of manufacture it is one or all of these that the law has

in view."

§ 71. Definition of a Design.

The design of an article whatever it be, is the appearance of the thing, as distinguished from its structure; and according to the above quoted decision a design to be patentable under the Act of 1842 must have been decorative as distinguished from useful, and consequently only those designs were patentable under this decision which are decorative. While this decision was apparently required under the language of the Act of 1842, it does not follow that it applies to all cases which may arise under the language of the Act now in in force. U. S. Revised Statutes, § 4929. Every mechanic and manufacturer knows that there are multi