5. (Apothecaries’ Hall.) Quicksilver, 50 lbs., and sulphuric acid, 70 lbs., are boiled to dryness in a cast-iron vessel; of the dry salt,
62 lbs. are triturated with quicksilver, 401⁄2 lbs., until the globules are extinguished, when sodium chloride, 34 lbs., is added, and after thorough admixture the whole is sublimed, &c., as before.—Prod. 96 to 100 lbs.
6. (Jewel’s Patent.) The receiver, which is capacious, is filled with steam, so that the calomel vapour is condensed in it in a state of extremely minute division. The engr. represents the apparatus now usually employed when this plan is adopted. The product is extremely white, and of the finest quality. It is sometimes called ‘hydrosublimed calomel’ and ‘hydrosublimate of mercury.’ The ‘flowers of calomel,’ of old pharmacy, were prepared in a nearly similar manner.
a. Furnace.
b. An earthenware retort, having a short and wide neck, containing the ingredients for making calomel.
c. An earthen receiver, having three tubulatures.
d. A vessel containing water.
e. A steam-boiler.
7. (Soubeiran.) The crude calomel mixture is heated in an earthen tube in a furnace, and a current of air is directed uninterruptedly into the tube by means of a small ventilator. This sweeps away, as it were, the vapours of calomel, and in a straight tube will carry them a distance of 60 feet, to avoid which the end of the recipient is immersed in water, by which means the calomel is moistened and falls down. This plan, slightly modified, is now extensively adopted in this country.