275
The hydrate of potash is thus composed:—
Hydrate of Potash . . 1 . 57 . 100*0 ..... 100
The strength of the liquor potasses may be ascertained by taking itssp. gr. The following extract from Mr. Dalton’s table (Neiv System ofChem. Philos, part ii. p. 476) illustrates this:—
Atoms.
Potashper cent, byweight.
Spec. Gravity.
Potash.
Water.
i
8
39-6
1-47
265 deg.
i
10
34-4
1-42
246
26-3
1-33
229
19-5
1-23
220
13-
1 • 15
215
9'5
111
214
4-7
1-06
213
Jlence it appears that the liquor potassa) of the London Pharmacopoeia,whose sp. gr. is T063, consists of—
Physiological Effects, (a.) On vegetables. —Caustic potash promptlydestroys the parts of living plants with which it is placed in contact, andeven in the dilute state kills haricots ( Phaseolus vulgaris) in a few hours.(Marcet, in Decandolle, Phys. Veget.)
(b.) On animals generally. —It acts on animals generally as an ener-getic caustic poison. It is, says Orfila ( Toxicol. Gener.), of all poisons thatwhich most frequently perforates the stomach. He found that injected intothe jugular vein of a dog it coagulated the blood, and caused speedydeath. It is, however, remarkable that when mixed with the bloodout of the body, it not only does not coagulate it, but actually preventsits spontaneous coagulation. Magendie has observed that by the exhi-bition of alkalies to dogs, the urine acquires alkaline properties.
(c.) On man. —The local action of caustic potash is exceedingly ener-getic. This is especially the case with solid potash. The alkali, ofcourse, neutralizes any free acid in the part to which it is applied, anddecomposes whatever ammoniacal salts may be present, causing theevolution of ammoniacal gas. Its chemical action on the organizedtissues is most powerful, as may be well illustrated by experiments. Thus,if a little potash solution be rubbed between the fingers, the epidermisbecomes corroded and dissolved, and a soapy feel is thereby produced.If a piece of fibrin (muscle, for example) be digested in a solution ofpotash, an unpleasant ammoniacal odour is evolved, a little alkaline