In a previous chapter, I gave a full account of the experiments made at Hallett’s Point, New York. On that occasion, General Newton, of the United States Engineers, reported to me that he considered that Nitro-Glycerin, in point of economy and power, had the advantage over both dualin and powder even when supplemented by fulminating fuse. The advantages claimed (only by the inventor) for dualin, are, that it is cheaper, safer, and more powerful than Nitro-Glycerin, and some experiments made in Prussia, are adduced in proof. I have to observe, on this point, that the Nitro-Glycerin made by the Nobel process, probably used in Prussia, is very inferior to the Tri-Nitro-Glycerin made by my process, both in stability and in explosive force, and it is much more readily exploded, fifteen grains of fulminate of mercury being necessary to ensure explosion of this latter, without chance of failure. Nobel’s Nitro-Glycerin is said to expand when solid, in which state the slightest friction is said to explode it, while Mowbray’s Tri-Nitro-Glycerin actually contracts about one-tenth in bulk when solidifying, and cannot be exploded when in the solid state, except by a heavy charge of fluid Nitro-Glycerin fired with it. Nobel’s preparation is yellow, and gives off nitrous fumes, and is claimed by the patentee to solidify at 50°F, while Mowbray’s is colorless as water and solidifies at 45°F. It may be possible, but not probable, therefore, that Nobel’s Nitro-Glycerin is inferior to Dittmar’s dualin, as used in Prussia; the latter then said to have been a preparation of nitrate of ammonia, sawdust immersed in sulpho-nitric acid and Nitro-Glycerin: but that 40 per cent. of washed sawdust (not treated with sulpho-nitric acid), moistened with 60 per cent. of a dark colored and evidently impure Nitro-Glycerin, and such was Dittmar’s dualin analysed by me, should surpass, in blasting, a chemically pure Nitro-Glycerin, is to expect 60 cents of currency to have more value than 100 cents of gold, or that a part is greater than the whole. As I have above referred to my analysis of Mr. Dittmar’s dualin, I will give in full the process and result of the same, for the benefit of the reader.