Sulphur is by nature the food of fire, and one of the principal ingredients in gunpowder, and in almost all compositions of fire-works; therefore, great care ought to be taken of its being good, and brought to the highest perfection. Now, to know when the sulphur is good, you are to observe that it be of a high yellow; and if, when held in one's hand, it crackles and bounces, it is a sign that it is fresh and good: but as the method of reducing brimstone to a powder is very troublesome, it is better to buy the flour ready made, which is done in large quantities, and in great perfection; but when a great quantity of fire-works is to be made, it is best to use the lump brimstone ground, in the same manner as gunpowder. _Of Saltpetre._ Saltpetre being the principal ingredient in fire-works, and a volatile body by reason of its aqueous and aërial parts, is easily rarefied by fire; but not so soon when foul and gross, as when purified from its gross and earthy parts, which greatly retard its velocity; therefore, when any quantity of fire-works is intended to be made, it would be necessary first to examine the saltpetre; for if it be not well cleansed from all impurities, and of a good sort, your works will not have their proper effect. _To pulverize Saltpetre._ Take a copper kettle, the bottom being spherical, and put into it fourteen pounds of refined saltpetre, with two quarts or five pints of clean water; then put the kettle on a slow fire, and when the saltpetre is dissolved, if any impurities arise, skim them off, and keep constantly stirring it with two large spatulas, till all the water exhales; and when done enough, it will appear like white sand, and as fine as flour; but if it should boil too fast, take the kettle off the fire, and set it on some wet sand, which will prevent the nitre from sticking to the kettle. When you have pulverized a quantity of saltpetre, be careful to keep it in a dry place. _To prepare Charcoal for Fire-works._