[ 3i ] 



or reddifh powder; where there is a consider- 

 able quantity of the volatile alkali, the water 

 turns blue by the addition of copper. When 

 this alkali is in a very fmall proportion, fome 

 of the water fhould be diftilled over. 



3. Neutral salts are frequently found in 

 medicinal waters. 



a. Glauber's salt, compounded of vitriolic 

 acid, and fixed foffil alkali ; fpirit of wine added 

 to a folution of this fait, precipitates it in a white 

 powder \ but no change is produced by the ad- 

 dition of any alkaline fait. 



b. Epsom salt, formed of the fame acid, and 

 the earth of magnefia, is often a compofition in 

 purging waters. Any alkaline fait, either fixed 

 or volatile, turns this water milky or curdly ; the 

 alkaline fait uniting with the vitriolic acid, pre- 

 cipitates the earth of magnefia. 



c. Nitre, is compofed of the nitrous acid, and 

 fixed alkali. Water containing this fait fhould 

 be evaporated, and the nitre remaining may be 

 known by deflagration, or by its making a 

 crackling noife over the fire. When the nitrous 

 acid is combined with calcareous earth inftead 

 of the fixed alkali, the earth may be precipitated 

 by the addition of this alkali. 



d. Common salt, confirming of the muriatic 

 acid, and foffil alkaline fait. The acid of this 

 fait is nicely detected by a folution of filver 

 in the nitrous acid; the muriatic acid, having 

 a nearer affinity with filver than the nitrous, 

 unites with the filver, which falls down in a white 

 fediment, while the nitrous acid joins with the 

 alkali of the common fait. It is proper to have 

 a redundancy of the nitrous acid in the folution 



of 



2 



