Читать книгу Gunpowder and Ammunition, Their Origin and Progress - H. W. L. Hime - Страница 11

A. Preparation of grough from natural saltpetre.

If natural saltpetre is dissolved in boiling water, cleansed, and passed through a filter, and boiled for a day and a night; the (grough) saltpetre will be found deposited in crystals at the bottom of the vessel.

The original is as follows:—

“Nota, quod sal petrosum est minera terræ et reperitur in scrophulis contra lapides. Hæc terra dissolvitur in aqua bulliente, postea depurata et distillata per filtrum et permittatur per diem et noctem integram decoqui, et invenies in fundo laminas salis conielatas cristallinas.”40