Page:Experimental researches in chemistry and.djvu/46

1820.] alone, it is not, in the first case, of sufficient quantity, and in the second, it would be diminished by dilution.

It is probable that if the tints produced be compared exactly with those occasioned by alkalies, slight differences might be perceived among some of them; or that if the properties of the altered colouring matter were examined, they would be found different with the different substances, as M. Desfosses has shown with regard to boracic acid and other acids; but my object has not been to trace these changes as far as possible, but merely to show their general appearance; to guard against any deceptive conclusion with respect to solutions tested by turmeric; and to call attention to the distinguishing characters of acids and alkalies.

Action of Salts on Turmeric Paper

the salts not alkaline, which have the power of affecting turmeric paper like alkalies (see pp. 29, 30), those of uranium are perhaps most powerful. The muriate, sulphate and acetate affect turmeric paper strongly even when considerably diluted; but the nitrate is the most powerful. A strong solution scarcely seems to have its power diminished by dilution with ten or twelve times its weight of water, and even when the solution contains only $1⁄600$ of dry nitrate of uranium, it sensibly browns turmeric paper.

The muriate of zirconia also possesses this same property to a considerable degree.

On the Decomposition of Chloride of Silver by Hydrogen and by Zinc.

some time ago communicated to me a mode of reducing chloride of silver by hydrogen. In a few experiments made some time since, in consequence of this communication, I found myself unable to decompose the chloride by a stream of pure hydrogen gas, or by allowing an atmosphere of the gas to remain for a long time in contact with it; I supposed, therefore, that the effect was produced by the hydrogen in its