Napier, James, 1810-1884, Fesquet, A. A · Philadelphia : H. Carey Baird · leaf 160
to the excess of sulphur over the iron, there is generally in the solution an ex- cess of acid, with, also, some persalt of iron, and often small quantities of copper, which would be deleterious. To get rid of this, a quantity of old iron is put into the solution, which takes up the excess of acid… … The solution is then evaporated to a proper density and crys- tallized. This method of adding old iron to produce the changes described, not being in all cases adopted, gives rise to some of the varieties of copperas found in the markets, concern- ing which there is much prejudice in the minds of…
Dyes and dyeing · Coal-tar colors
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