352 ESSAYS AND OBSERVATIONS 



Jpir,faL ammon, it becomes a medicine 

 much of the fame nature with the pre- 

 ceeding white precipitate. A folutioii 

 of crude fait ammoniac and fpi?-. JaL 

 mar, have the fame efiPeds on the folutioii 

 of quick filver, as the muria has. 



If a little frefh urine is put into a fo- 

 lution of quick-filver in aqiia fortis^ there 

 will likewife happen a precipitation: 

 But the powder is not white, but of a 

 pink or flefliy colour ; it appears pretty- 

 bulky, and has acquired a little additio- 

 nal weight. This precipitate is not ufu- 

 ally prefcribed by phyficians : But M. 

 Lemery pretends that it is milder than 

 the white, and only operates by ftool. 



It would appear then, that, in many 

 inftances of precipitation, the particles of 

 the diffolved bodv are increafed in denfi- 

 ty and fpecific gravity; by reafon that 

 fbme parts either of the precipitating 

 matter only, or of the compound, made 

 up of the folvent and precipitant, are ve- 

 ry firmly united to them, fo that they 

 cannot longer be fuftained in the liquor. 

 But, in other cafes, where the matter prd^- 



cipi^ 



