414

ELEMENTS OK MATERIA MEDICA.

Antidotes. —The antidotes for hydrosulphate of ammonia, as well as for hy-drosulphuric aeid, are chlorine and the Chlorides of lime and soda. In cases ofasphyxia by the Inhalation of these substances, the treatraent consists in placingthe patient on bis back in the open air, with his head somewhat elevated; apply-ing cold affusion to the face and breast; producing artificial rcspiration of' air,through which chlorine is diffused, by pressing down the ribs and forcing up thediaphragm, and then suddenly removing the pressure; using strong friction in thecourse of the vertebral column, ehest, soles of the feet, &c, and injeeting intothe stomach, stimulants; as, a weak Solution of chlorine (or of chloride of lime)or brandy, &c. In the event of hydrosulphuret of ammonia being by aeeidentswallowed in poisonous doses, dilute Solutions of chlorine, or of the Chlorides oflime and soda, should be immediately given, and the contents of the stomach re-moved by the stomach-pump as soon as possible.

Order XI. COMPOUNDS OF POTASSIUM.

1. POTAS'S,E HY'DRAS, i.—HYDRATE OF POTASH.

(Potassa, E. (TT. S.)—Potassa caustica, £>.)

History. —Caustic alkaline Solutions were probably known to the Greeks andRomans. We learn from Pliny (Bist. Nat. lib. xxviii. cap. 51.) that soap wasmade in his time from tallow and woqd-ashes; and we may therefore concludethat some method was known of depriving the alkaline carbonate of its carbonicaeid. Geber (Invention of Verity, eh. iv.) describes the method of makingcaustic alkali. Black, however, in the year 1756, first distinguished, chemically,the caustic alkalis from their carbonates. Potash was formerly called kali, orthe vegetable alkali. It is the Protoxide of Potassium.

Natural History.— Potash in combination with aeids is found in both king-doms of nature.

a. In the Inokganized Kikgdom. —Potash is found, in the minoral kingdom, in combina-tion with sulphuric, nitric, silicic, and perhaps carbonic aeids. As an ingredient of rocke, itis more abundant than soda.

ß. In the Ouganized Kingdom. —In organized beings potash is met with in combinationwith phosphoric, sulphuric, nitric, carbonic, and various organic aeids. It oeenrs more abun-danfly in vegetables than in animals.

Preparation. —All the British Colleges give directions for the preparation ofhydrate of potash.

The London College orders, of Solution of Potash, a galion. Evaporate the water in aclean iron vessel over the fire, until the ebnllition being finished, the Hydrate of Potash lique.lies : pour this into proper moulds. [This is tbe direction of the U. S. P.]

The Edinburgh College directs any convenient quantity of aqua Potassa? to be evaporatedin a clean and covered iron vessel, increasing gradually the heat tili an oily-looking fluid re-mains ; a drop of which, when removed on a rod, becomes hard on eooling; then pour out theliquid upon a bright iron plate, and as soon as it soiidifies break it quickly, and put it into glassbottles secured with glass Stoppers.

The process of the Dublin College is essentially the 9ame as that of the Edinburgh College,except that the evaporation is to be effected in vessels of silveror iron, and the liquefied potashis to be poured out on a plate of silver or iron.

Properties. —The solid hydrate of potash of the shops, known as Potassa fusa{Kalipurum; Lapis Infernalis sive Septicus; Cauterium Potentiale)isusual]y moreor less coloured (brownish, grayish, or bluish,) and not completely soluble in waterand alcohol in consequence of the presence of foreign matters. Pure hydrate ofpotash, however, is white, and dissolves in both water and alcohol. During itsSolution in water, heat is evolved. Its solubility in alcohol enables tts to separateit from the carbonate and bicarbonate of potash, both of which are insoluble in thisliquid. It has a strong affinity for both water and carbonic aeid, which it rapidlyattracts from the atmosphere, and in consequence becomes liquid. At a low red

r"

t