ANALYSIS OF ORES OF ZINC.

ANALYSIS OF ORES OF ZINC.

I*'or extracting zinc from the ore called llende, let one part ofthe powdered ere be gently boiled in six of diluted nitric acid ina flask to dryness, and repeat this operation with the same oretwo or three times. Then dissolve the dry mass in a suffi-cient quantity of water to which about one-fourth part of nitricacid has been added, and precipitate the fluid by a solutionof soda. Collect the precipitate on a filter, wash it by pas-sing water over it, and re-dissolve it in muriatic acid. Thendecompose this solution by liquid ammonia in excess, in orderto separate the iron, lead, and alumine which may have beendissolved. If this precipitate be boiled in four times its quantityof potash tiie alumine will be separated.

From the before-going solution the zinc may be separated bythe addition of an acid. It may be reduced to the metallic stateby strongly igniting it with half its weight of charcoal in a closedcrucible.

In order to analyze calamine, let it be digested repeatedly indiluted nitric acid, and the insoluble residue be boiled in con-centrated muriatic acid three times. What remains after ablu-tion w’ith boiling water is silex.

The nitric solution obtained before, contains the zinc, and alsoiron and alumine, if they were present in the ore. Let there-fore the solution be evaporated to dryness, re-dissolve it in nitricacid, and evaporate it again as before, in order to render theiron as insoluble as possible. Then dissolve the mass in u'ater.

A tolerably exact assay of the ore called calamine, may bemade in the following manner:

Mix any quantity of the pulverized ore, previously freed fromsulphur by roasting, with one-eighth part of charcoal powder.Put this mixture into a crucible capable of containing thrice thequantity. Diffuse equally amongst this mixture a quantity ofsmall grains or thin plates of copper equal to that of the cala-