PHYSICAL AND LITERARY. 183 



down to the bottom of the vefTel along with 

 the earth of alum which is deprived of its 

 acid. . The light cloud formed by the alkali 

 proceeds from the minute portion of the 

 calcarious compound which faturates the 

 water. 



The earth of animal bones, when reduced 

 to a fine powder and thrown into a diluted 

 vitriolic acid, gradually abforbs the acid in 

 the fame manner as the calcarious earths, 

 but without any remarkable effervefcence. 

 When it is added to the nitrous or to the 

 muriatic acid, it is llowly diffolved. The 

 compound liquor thence produced is ex- 

 tremely acrid, and ftill changes the colour of 

 the juice of violets to a red, even after it is 

 fully faturated with the abforbent. Diftilled 

 vinegar has little or no effed: upon this earth; 

 for after a long digeflion it ftill retains its 

 four tafte, and gives only a light cloud upon 

 the addition of an alkali. 



By dropping a diffolved fixed alkali into a 

 warm folution of alum, I obtained the earth 

 of this fait, which, after being well waihed 

 and dried, was found to have the following 

 properties. 



It 



