First you must have some filtring bags, hung on a rack, with glazed earthen pans under them, in the same manner as those for refining saltpetre: then take any quantity of damaged powder, and put it into a copper, with as much clean water as will just cover it; and when it begins to boil take off the scum, and after it has boiled a few minutes, stir it up; then take it out of the copper with a small hand kettle for that purpose, and put some into each bag, beginning at one end of the rack, so that by the time you have got to the last bag, the first will be ready for more; continue thus, till all the bags are full; then take the liquor out of the pans, which boil and filter, as before, two or three times, till the water runs quite clear, which you must let stand in the pans for some time, and the saltpetre will appear at top. Now to get all the saltpetre entirely out of the powder, take the water from the saltpetre already extracted, to which add some fresh water and the dregs of the powder that remain in the bags, and put them together in a vessel, to stand as long as you please, and when you want to extract the nitre, you must proceed with this mixture as with the powder at first, by which means you will draw out all the saltpetre; but this process must be boiled longer than the first. Of SULPHUR, or BRIMSTONE. Sulphur is by nature the food of fire, and one of the principal ingredients in gunpowder, and almost in all compositions of fireworks; 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 to do, it is better to buy the flower ready made, which is done in large quantities, and in great perfection: but when a grand collection of fireworks are to be made, the strongest and best sulphur to use, is the lump brimstone ground in the same manner as gun powder, which we shall treat of in the following part of the treatise. How to prepare CHARCOAL for Fireworks.