Solubility.—Tartar emetic is almost insoluble in alcohol, and still less soluble in ether, chloroform, &c. Spirits and water, such as are mixed for drinking, dissolve nearly as much as cold water, and more if warm. The solubility in cold water is given very variously in the text-books, from 1 part in 21·8 —“20 grains per fluid ounce,” British Pharmacopœia), 1 in 20 (Garrod and Blyth), 1 in 15 (Brande’s and Gmelin’s Chemistry), to 1 in 14 (Graham and Taylor). To clear up this difficulty I prepared for Dr. Bernays in 1879 a very pure sample of the salt: he found that 100 cubic centimetres of water at 58° F. dissolved 6·67 grammes, equal to one part in fifteen. The solubility rises rapidly with the temperature, till it reaches one part in two at the boiling point. The discrepancies are accounted for by the facts that, (1), the textbooks do not mention the temperature; (2), the salt readily effloresces in air, losing water and becoming less soluble; (3), impurities are often present.
Composition.—Commercial tartar emetic is generally very pure. It sometimes contains a trace of sand and dirt, occasionally an excess of cream of tartar (potass. hydrogen tartrate) from careless preparation, but I have never found arsenic. The theoretical percentage of Sb is 36·53: in good commercial samples Bernays found 36·03 to 36·32 per cent.; in an over-dried specimen, 37·4 per cent. One sample contained 23 per cent. of cream of tartar and only 28·13 of Sb; another, 10 per cent. tartar and 32·7 of Sb.
USES AND OCCURRENCE.
The alloys and pyrotechnic uses have been already mentioned. The impure fused sulphide (vitrum antimonii) is employed to give a yellow tint to glass and porcelain. The oxides are used in glazing earthenware, and in glass and china painting. The following are antimonial pigments: “Antimony cinnabar,” and “crocus,” or “saffron of antimony,” are oxysulphides: “Naples,” “Cassell,” and “antimony yellows,” are chiefly antimoniates of lead. Small quantities of antimony occur in iron ores, ferruginous waters, the coal formation, and in river sand (Roscoe).
In veterinary practice, large doses of antimonials are given to animals, as much as 90 grains of tartar emetic being often administered to a horse in his gruel three times a day. Other preparations are used (see Blyth’s Pract. Chem. 1879, p. 404). They are supposed to cause fattening.
Medicinally it is employed in typhus, delirium tremens, small doses in croup and the broncho-pneumonia of children, as a general expectorant in asthma and bronchitis, in whooping-cough, by some recommended also in scaly skin affections. In acute inflammations and pneumonia, it has lost favour, as too depressing (Farquharson’s Therapeutics). In times before chloroform, tartar emetic was even used to lower the muscular tension previous to reducing dislocations.
DOSES AND PREPARATIONS.
Pulvis antimonialis, 3 to 10 grains. This is the Pharmacopœial equivalent of “James’s Powder,” a secret remedy once highly popular. It contains one part of Sb2 O3 to two of phosphate of lime.
Vinum antimoniale, antimonial wine, is a solution of 10 grains of tartar emetic to each ounce of sherry: dose, 5 minims to 1 fluid drachm.