Chap. 7.] [ 33 J 



CHAP. VII. 



MURIATIC SALTS. 



Sal Digeflivus Common Salt. Rock Salt. Natural Hiftcry cf 

 Salt. Sdltnefs of the Ocean. Ufes of commcn Salt in the drts> 

 Sal /Immoniac. Natural Hijlory nf Sal Ammoniac. 



r I ^HE combinations of the muriatic acid with the 

 JL alkalis are, ift, SAL DIGESTIVUS, or muriat of 

 pot-am, which has al'fo been called the febrifuge fait 

 of Sylvius, and is a compofition of the muriatic acid 

 with the fixed vegetable alkali. Its tafte is penetrat- 

 ing and bitter ; its cryftals cubical, but almoft always 

 confufed and irregular. In the fire it decrepitates, that 

 is, its cryftals fuddenly break and fly in pieces by the 

 rarefaclion of the water which enters into their com- 

 pofition. If the heat is then continued, and diffidently 

 ftr'ong, it melts, and is volatized without decompofi- 

 tion. It is not much altered by expofuie to the air ; 

 It is however (lightly deliquefcent. About three parts 

 of cold water are required to hold one part of this fait 

 in folution, and hot water dees not diflolve a greater 

 'quantity. 



Clay appears to decompofe this fait in part, for ma- 

 rine acid is obtained by diftilling it with the clays found 

 in the vicinity of Paris. This operation, however, in 

 ifaft affords only a fmall quantity of acid, and land feems 

 to have a fimilar effecl. Ponderous earth ieizes its acid, 

 and feparates the alkali, according to Bergman. Mag- 

 nefia and lime do not at all change it. The vitriolic 

 and nitrous acids difengage the muriatic acid with 

 effervefcence. This fait is found in a Hate of nature, 



VOL. II. D buc 



