United States patents
UNITED STATES PATENT OFFICE
ALFRED NOBEL, OF HAMBURG, GERMANY, ASSIGNOR TO JULIUS BANDMANN, OF SAN FRANCISCO, CALIFORNIA.
Letters Patent No 78,317, dated May 26, 1868.
IMPROVED EXPLOSIVE COMPOUND.
The Schedule referred to in these Letters Patent and making part of the same.
TO ALL WHOM IT MAY CONCERN :
Be it known that, I, Alfred Nobel, of the city of Hamburg, Germany, have invented a new and useful Composition of Matter, to wit, an Explosive Powder.
The nature of the invention consists in forming out of two ingredients long known, viz, the explosive substance nitro-glycerine, and an inexplosive porous substance, hereafter specified, a composition which, without losing the great explosive power of nitro-glycerine, is very much altered as to its explosive and other properties, being far more safe and convenient for transportation, storage, and use, than nitro-glycerine.
In general terms, my invention consists inmixing with nitro-glycerine a substance which possesses a very great absorbent capacity, and which, at the same time, is free from any quality which decompose, destroy or injure the nitro-glycerine or its explosiveness.
It is undoubtedly true, as a general rule, that nitro-glycerine, when mixed with another substance, possesses less concentration of power than when used alone ; but while the safety of the miner (to prevent leakage into seams in the rock) prohibits the use of nitro-glycerine without cartridges, which latter must of course be somewhat less in diameter than the bore-holes which are to contain them, the powder herein described can be made to form a semi-pasty mass, which yields to the alightest pressure, and thus can be made to fill up the bore-hole entirely. Practically, therefore, the miner will have as much nitro-glycerine in the same height of bore-hole with this powder as with nitro-glycerine in its pure state.
This is the real character and purpose of my invention ; and in order to enable others skilled in the art to which it appertains (or with which it is most nearly connected) to make, compound, and use the same, I will proceed to describe the same, and also the manner and process of making, compounding, and using it, in full, clear, and exact terms.
The substance which most fully meets the requirements above mentioned, so far as I know or have been able to ascertain from numerous experiments, is a certain kind of silicious earth or silicic acid, found in various parts of the globe, and known under the several names of silicious marl, tripoli, rotten-stone, &c. The particular variety of this material which is best for my compound is homogeneous, has a low specific gravity, great absorbent capacity, and is generally composed of the remains of infusoria.
So great is the absorbent capacity of this earth, that it will take up about three time its own weight of nitro-glycerine and still retain its powder-form, thus leaving the nitro-glycerine so compact and concentrated as to have very nearly its original explosive power ; whereas, if another substance, having a less absorbent capacity, is used, a correspondingly weak or wholly inexplosive.
For example, most chalk will take but about fifteen per cent of nitro-glycerine and retain its powder-form, twenty per cent, will reduce it to a paste.
Porous charcoal has also a considerable absorbent capacity, but it has the defeet of beeing itself a combustible material, and also of less elasticity of its particles, which renders it easy to squeeze out a part of its nitro-glycerine.
The two materials are combined in the following manner :
The earth, thoroughly dried and pulverized, is placed in a wooden vessel. To it is introduced the nitro-glycerine in a steady stream so small that the two ingredients can be kept thoroughly mixed.
The mixing may be effected by the naked hand, or by any proper wooden instrument used in the hand, or by wooden machinery.
Sufficient of nitro-glycerine should be used to render the compound explosive, but not so much as to change its form of powder to a liquid or pasty consistency.
Practically, about sixty parts, by weight, of nitro-glycerine to forty of earth, forms the useful minimum, and seventy-eight parts, by weight, of nitro-glycerine to twenty-two of earth, the useful maximum of explosive power. The former has a perfectly dry appearance, the latter is pasty.
Between these two extremes the composition will be explosive powder, and it will be more easily exploded, and its explosive power greater, as the relative proportion of the nitro-glycerine is greater.