[24] urine and dung of the animals, which will produce Sal-amoniac instead of Salt-petre[1]; and it is considered as a rule for the choice of materials, that the longer they have lain together, the greater chance there will be of getting Salt-petre out of them.
When the materials are collected, they extract and refine the Salt-petre by the following easy process, which I shall divide into six parts, to render it plain and easy of comprehension, viz.
1. To make the Lye.
2. The first boiling to prepare it for filtering.
3. Filtering or straining the Lye.
4. The second boiling to separate the sea-salt and preparing it for crystalizing.
5. Crystalizing the Salt-petre
6. Refining the crystals of Salt-petre.
First, To make the Lye.
Take a tub or tubs, according to the extent of your works, but not to exceed the size of half a hogshead in depth, make a hole in the bottom near one edge, fit a plug or spigot to it, lay a wisp or straw over this hole, then fill the tub tightly with the earth which you have found to contain Salt-petre, pour as much cold water on it as will fill the tub to the brim, after it has soaked into the earth, keep your tubs in a warm place, that the water may not freeze, and in about ten or twelve hours draw off the water at the hole in thebottom,
- ↑ At the Provincial Works in the city of Philadelphia, cellar dirt is chiefly used as it has been found to contain a greater proportion of Nitre than any other earth they have met with.
