As Dualin is the only one of these compounds that has been attempted to be brought in any way into competition with Nitro-Glycerin, in the Eastern States, a synopsis of the results may possess interest. Some six different parcels of dualin in all, have been experimented with at the Hoosac Tunnel, and of these the first shipment, being useless at the West End, was forwarded to the Central Shaft, and there again tried, but the effects, as compared with the Nitro-Glycerin supplied by the writer, were not such as to justify the contractors in continuing its use, consequently it was thrown out. Another parcel, intended to be stronger, shipped in the hot summer of 1870, exploded in the cars in transit at Worcester, proving, what had been suspected from a perusal of the dualin patents, that the inventor was really ignorant of the properties of the materials of which his combination was composed. From evidence adduced at Worcester, given by the compounder of dualin, and also by a manufacturer of exploders, some of whose wares were in the same car, it appeared that the Nitro-Glycerin exuding from the mixture of sawdust (40 per cent.) and Nitro-Glycerin (60 per cent.) of which the dualin, made at that time by Mr. Dittmar, was composed, flowed in a pool on the floor of the car, and, when the cars were set in motion, a series of sharp detonations ensued, probably from this pool of Nitro-Glycerin running on to the wheels and being compressed or hammered during the revolution of the car wheels on the rails, firing the pool, which in turn fired the whole shipment of dualin, together with the exploders.