654 ORD. XL. Oleracec. SALSOLA KALI. 
ponderous, sonorous, dry to the touch, and externally abounding | 
with small cavities, without any offensive smell, and very salt to 
the taste; if long exposed to the air, it undergoes a degree of 
spontaneous calcination. . The best French Soda is also dry, 
sonorous, brittle, and of a deep blue colour, approaching to black. 
' The Soda, which is mixed with small stones, which gives out a 
fetid smell on solution, and is white, soft, and Beliquescent; is of 
the worst kind.* 
The method of purifying this salt is directed in the London 
Pharm. under the article of Natron preparatum, and in the 
Edinburgh Pharm. under that of Sal alkalinus fixus fossilis puri- 
ficatus: the pure crystals, thus formed of Alicant barilla, are 
colourless, transparent, lamellated, of a rhomboidal figure, and one 
hundred parts are found to contain twenty of alkali, sixteen of 
aerial acid, and sixty-four of water;° but upon keeping the 
crystals for a length of time, if the air be not excluded, the water 
evaporates, and they assume the form of a white powder. Accord- 
ing to Imlin,’ one ounce of water, at the temperature 62 of Fahr. 
dissolves five drams and fifteen grains of the crystals.~ The same 
author also coninvon mlgeahougl ict or NE apecaaalga 
longer than common salt, though not so longa etabl 
alkali. Natron has been thought useful in scrophulous disorders, 
but it is seldom given in its simple state. 
In combination with vitriolic acid this alkali forms Glauber salt, 
or Natron vitriolatum; with nitrous acid, cubic nitre; with marine 
acid, common salt; with the sedative salt of Homberg, borax; with 
cream of tartar, Rochelle salt, or sel saignette. 
To enter fully on the peculiar properties, or chemical qualities, 
of this alkali, would lead us too far, and is properly.the province 
* For this, and almost the whole on this subject, we are obliged to the late 
Professor Murray. See his App. Med. vol. 4 
° Bergman in Scheffers. P Diss. de Soda. §. 2. 
+t Kirwan says, 2, 5 times its weight of water at this temperature are required. 
Min, p. 176. 
