J. E. de Vrij also, in a communication to the British Association, which was read in July, 1851, and is published in the report of the association for the year 1851, page 52 (Notices and Abstracts), states in regard to Nitro-Glycerin, that it “explodes at a moderate heat, as was shown by experiment, detonating when the drops of Nitro-Glycerin on paper were struck a smart blow with a hammer.” The before-mentioned re-issued patents further assert that “in order to explode the whole, or even a large proportion of the mass of Nitro-Glycerin, it is necessary to subject it to confinement or restraint”; which assertion is untrue, for Nitro-Glycerin, when freely exposed to the air in an open vessel or plate, may be and is capable of being readily exploded, without confinement, restraint, or pressure, as I have proved by experiment made at North Adams, on the 17th day of May, 1870, in exploding upon two occasions a quantity of Nitro-Glycerin in an open saucer with great violence, on which occasion the Nitro-Glycerin was exploded by simple concussion in open vessels, the fulminate cap used as the exploder being suspended above the surface of the Nitro-Glycerin in the saucer, and distant nearly two inches from it; so that the application of heat and pressure, or of either of these agencies, is unnecessary. The said re-issued patents further assert, that “the degree of confinement must be sufficient to allow a pressure upon the Nitro-Glycerin to an extent that 360°F will be realized, so that decomposition will take place before the liquid can escape the force or heat of the evolved gases of a percussion cap, etc.”; whereas I found on the above occasion that when water was interposed between the Nitro-Glycerin and the percussion cap, so that no measurable increase of temperature (much less 360°F) could possibly occur in the former, the Nitro-Glycerin could be exploded. In the first experiment three tubes, closed at bottom and containing half an ounce of Nitro-Glycerin each, were placed in water in a tumbler, being supported an inch from the bottom. Into the water in the tumblers, and outside of the tubes, distant from them nearly an inch, the fulminate cap was put. This was then fired, and caused the explosion of the Nitro-Glycerin through the intervening water. In the second experiment, using a tub of water in which eleven tubes containing Nitro-Glycerin were placed, the explosion of six fulminate caps failed to fire the Nitro-Glycerin, the distance from the tubes at which they were placed, nearly or quite ten inches, being too great. In the third experiment five such tubes of Nitro-Glycerin were suspended in a tub of water distant four or five inches from each other; the fulminate cap being inserted in the middle tube. On firing this cap the Nitro-Glycerin in all the tubes was exploded, as judged from the violent effects produced.