The sal grows to a large size, and is more gregarious than the teak.
The celebrated Gascoigne's powder, which was sold as late as the middle of the 19th century in the form of balls like sal prunella, consisted of equal parts of crabs' eyes," the black tips of crabs' claws, Oriental pearls, Oriental bezoar and white coral, and was administered in jelly made of hart's horn, but was prescribed by physicians chiefly for wealthy people, as it cost about forty shillings per ounce.
Heating spirits of hartshorn, he was able to collect "alkaline air" (gaseous ammonia), again because he was using mercury in his pneumatic trough; then, trying what would happen if he passed electric sparks through the gas, he decomposed it into nitrogen and hydrogen, and "having a notion" that mixed with hydrochloric acid gas it would produce a "neutral air," perhaps much the same as common air, he synthesized sal ammoniac. Dephlogisticated air (oxygen) he prepared in August 1774 by heating red oxide of mercury with a burning-glass, and he found that in it a candle burnt with a remarkably vigorous flame and mice lived well.
It was first prepared by Wilhelm Homberg (1652-1715) from borax, by the action of mineral acids, and was given the name sal sedativum Hombergi.
Thus he clearly described the preparation of hydrochloric acid by the action of oil of vitriol on common salt, the manifold virtues of sodium sulphate - sal mirabile, Glauber's salt - formed in the process being one of the chief themes of his Miraculum mundi; and he noticed that nitric acid was formed when nitre was substituted for the common salt.