Twenty (20) grammes of dualin were allowed to digest in a glass tube for several days, covered with washed sulphuric ether. The ether was then drawn off, and the residue in the glass tube washed with ether until the cessation of the peculiar persistent taste of Nitro-Glycerin, causing the “Glycerin headache,” proved the Nitro-Glycerin was exhausted. The residual woody fibre was now dried thoroughly, and weighed eight grammes. A portion of it thrown on a red hot plate did not deflagrate; this indicated it had not been treated with nitric acid, and had not been converted into nitro-cellulose. Washed in distilled water, and the washings evaporated, no saline or crystalline salt was obtained. The residue, dried and thrown on a red hot plate, charred and burnt like any other sawdust. Now, I assert positively, the dualin I analysed, furnished by Mr. Dittmar himself for blasting in the Tunnel, was simply a compound of washed sawdust and Nitro-Glycerin (actually yellow fuming Nitro-Glycerin.) I have deemed it due to myself to extend these observations further than I intended, but, in the interest of truth, I could not permit the friendly notices of the press, which have been industriously secured, nor the biased views, of men employed in exploding, (to whom payment of ten dollars was promised, for every case of dualin used, to exaggerate results), to mislead mining contractors, and I stand prepared to prove that 100 parts dualin are only equal to 50 parts pure Nitro-Glycerin, for practical blasting purposes. Dualin is a mixture varying according to the humor of the compounder, but never exceeding one-half the strength of Tri-Nitro-Glycerin; it has all the danger of the Nobel Nitro-Glycerin, with the additional tendency to decomposition, sworn to by Mr. Dittmar himself at the Worcester investigation, owing to its being an admixture of organic matter with Nitro-Glycerin, and its inventor, (as evidenced by his patent, where he proposes to concentrate sulphuric acid, and free it from nitrogen, by boiling it with charcoal!), does not understand the properties of the commonest commercial compounds he undertakes to handle. These facts determine, I submit, the superior advantage of a uniform chemical product produced under invariable conditions, especially since it is more difficult to explode it, and it is proportionately safer, and, above all, has double the effective force. Mr. Dittmar’s promises have failed, and his representations have been disproved by the results at the Hoosac Tunnel. Up to October, 1870, he had six trials, of which he only claims one as a success, though he did succeed in inducing the employees to misrepresent the facts to the contractors, and thereby obtained a testimonial; but over two thousand pounds of his dualin was buried in the Berkshire mountains—a stern pecuniary lesson, verifying the truth of the old Roman apothegm, so much neglected in modern times—“Magna est veritas et prevalebit.” CHAPTER VII.