Art. XVI. Analysis of Wacke, by Dr. J. W. Webster, of Boston.

One hundred parts exposed to a red heat in a platina crucible lost 18.5, acquired an umber brown colour, and a degree of hardness sufficient to scratch glass.

One hundred parts reduced to fine powder were mixed with four times the weight of soda, and exposed to heat, gradually increased for three quarters of an hour; at the expiration of which time, the whole had acquired a pasty consistence. The crucible was now removed from the fire, its outer surface carefully wiped. Muriatic acid was poured on till all effervescence ceased. The solution obtained was evaporated to dryness, gradually assuming an orange red colour. Water was now poured upon the mass, after which it was filtered, and the powder remaining carefully dried; after ignition, and while warm, it weighed 28 parts. This powder was insoluble in muriatic acid, and of a white colour.

To the filtered solution, reduced by evaporation, carbonate of potash was added, the precipitate was collected on a filter, washed and dried; it weighed 23 parts. This powder was redissolved in sulphuric acid, sulphate of potash added, and crystals of alum finally obtained; hence this powder was alumine. To the liquor from which the silex and alumine had thus been separated, acetic acid was added; the whole evaporated to dryness; the excess of acid being removed, a small quantity of water was poured on, and after strong ignition, the precipitate weighed 4.5.

Into a very small tubulated retort I introduced a portion from the same mass, whence the piece submitted to analysis was broken, and obtained over mercury the carbonic acid in the usual manner. This was equal to 2.32; by deducting this from 18.5 the loss during exposure to red heat, we shall have 16.18, the proportion of water. The oxide of iron was separated from the solutions after the addition of acetic acid, by ammonia, and weighed 26 parts.

AGRICULTURE AND ECONOMICS.