A pair of scissors is required to trim the wick of the and for the trimming of the edge of platinum foil.
A small spatula should be kept for the purpose of mixing substances with fluxes.
THE REAGENTS.
Those substances which possess the property of acting upon other substances, in such a characteristic manner that they can be recognized, either by their color, or by their effervescence, or by the peculiar precipitation produced, are termed reagents. The phenomena thus produced is termed reaction. We use those reagents, or tests, for the purpose of ascertaining the presence or the absence of certain substances, through the peculiar phenomena produced when brought in contact with them.
The number of reagents employed in blowpipe analysis is not great, and therefore we shall here give a brief description of their preparation and use. It is indispensably necessary that they should be chemically pure, as every admixture of a foreign substance would only produce a false result. Some of them have a strong affinity for water, or are deliquescent, and consequently absorb it greedily from the air. These must be kept in glass bottles, with glass stoppers, fitted air-tight by grinding.
A. REAGENTS OF GENERAL USE.
1. Carbonate of Soda.—(NaO, CO2) Wash the bicarbonate of soda (NaO, 2CO2) upon a filter, with cold water, until the filtrate ceases to give, after neutralization with diluted nitric acid (NO5), a precipitate with nitrate of baryta, (BaO, NO5), or nitrate of silver, (AgO, NO5). That left upon the filter we make red hot in a platinum, silver, or porcelain dish. One atom of carbonic acid is expelled, and the residue is carbonate of soda.