1st. By the eprouvette of Darcy, consisting of a cannon, which, being suspended to the extremity of a bar of iron, described by its recoil an arc, of which the degrees can be measured. _Recoil._ 2 drachms muriatic powder, 15 deg. 2/20 2 ---- do do moistened, 14 -- 1/20 2 ---- common powder, 10 -- 7/20 2 drachms common powder, 10 -- 1/20 3 ---- muriatic powder, 20 -- 9/20 3 ---- common powder, 16 -- 6/20 From these results, it appears, that, by the eprouvette of Darcy, the muriated powder, or that prepared with chlorate of potassa, gave a superiority of force of about one-fourth. 2nd. By the eprouvette of Regnier, which is repelled by the explosion, to a distance greater or less, measured by the degrees of the arc which it describes: Muriated powder, 42 Idem, 51¾ Idem, moistened, 52 Common powder, superfine, 23 Idem, 22½ From which it results, that by the eprouvette of Regnier, the force of the powder of the oxymuriate is double that of the nitrate, or common powder. M. Ruggieri is of opinion, that chlorate, or hyperoxymuriate of potassa may be employed with advantage in the composition of rockets, but we have not heard that it has been used. It is more powerful in its effects, and probably for this reason he recommended it. This salt, mixed with other substances, will produce the _green fire_ of the palm-tree, in imitation of the Russian fire. Chloric acid may be obtained in a separate state, by boiling the compound solution formed by passing chlorine gas through a solution of barytic earth, with phosphate of silver, which separates the muriatic acid. By evaporation, the chlorate of barytes will crystallize in fine rhomboidal prisms. When these crystals are dissolved in water, and diluted sulphuric acid added by degrees, an acid liquid will be obtained, which, if the sulphuric acid be added cautiously, will be found entirely free from the latter acid and barytes, and not affected by nitrate of silver. This is the chloric acid dissolved in water. Chloric acid unites with sundry bases. Combined with ammonia, it forms a fulminating salt, formerly described by M. Chenevix. This salt is formed, by mixing together carbonate of ammonia, and chlorate of lime. The carbonate of lime is then separated by the filter, and the clear liquid, holding the chlorate of ammonia in solution, is evaporated. Chlorate of ammonia is very soluble in water and alcohol, and decomposed by a moderate heat. Chlorates, as the chlorate of potassa, are formed more readily in the manner already stated: _viz._ by saturating the base with chlorine, but in this case two salts are produced, the chlorate and hydrochlorate. Chloric acid has also been obtained in a separate state, from chlorate of potassa, by a process recommended by Mr. Wheeler.