5. Calcium, Commercial Sulphuret of. Syn. Commercial sulphide of calcium. Prep.—a. As 1, b (above).
b. Sulphur, 1 part; hydrate of lime, 3 parts; water, 21⁄2 pints; boil it until it solidifies on cooling, then pour it out on a cold marble slab, and when solid break it into pieces and preserve it in a well-corked bottle.
c. (Guibourt.) Quick-lime, 7 parts; sulphur,
4 parts; mix, and heat the compound for about 2 hours in a covered crucible.
d. (Cottereau.) Quick-lime, 2 parts; sulphur, 1 part; water, 5 parts; as 4, b (above).
Obs. The precise composition of the last three preparations is uncertain. They are acrid, caustic, stimulant, and diaphoretic. Dose, 1 to 3 gr. Sulphide of calcium has been used as a depilatory by applying it made into a paste with water, and washing it off in about 1⁄4 of an hour. Made into an embrocation, it has been strongly recommended in gout, scabies, &c. Its solution yields pure sulphur on the addition of hydrochloric acid.
CALCULA′TIONS (Useful). 1. To find the Value of a Dozen Articles. Take the price in pence as shillings, and if there are any farthings in the price, add threepence for each. Thus 2s. 8d., or 32 pence per yard, is £1 12s. per dozen.
2. To find the Value of One Hundred Articles. For every farthing take as many pence and twice as many shillings. Thus, 11⁄4d. each is—5d., and 10s. = 10s. 5d. per hundred.
3. To find the Value of a Pound at any price per Ounce. Take the price in farthings as shillings, and divide by three. Thus, 51⁄4d. per ounce is 21 farthings; taken as shillings, 21 ÷ 3 = 7s. per pound.
4. To find the Value of an Ounce at any price per Pound. Take the shillings as farthings, and multiply by three. Thus, at 6s.—6 × 3 = 18 farthings, or 41⁄2d. per ounce.