MURIATES AND CHLORIDES. 217 



the decomposed portion, then 12*75 parts of ' this chic 

 salt in crystals lose 6*75 parts, which is equiva- 

 lent to 6 atoms of water, and there remain 6 

 parts of chloride of magnesium, composed of 



1 atom chlorine 4*5 



1 atom magnesium 1-5 



When this chloride is thrown into water, a hiss- 

 ing noise takes place as when a red hot iron is 

 plunged into water ; a great deal of heat is 

 evolved, and the whole is gradually dissolved, 

 leaving behind always a portion of pure mag- 

 nesia, which I subtracted in the preceding state- 

 ments. 



7. Muriate of alumina. This salt is easily Muriate of 



1-11 -I'll alumina. 



obtained by saturating muriatic acid with hy- 

 drate of alumina. It is a beautiful white mat- 

 ter, without any appearance of a crystalline tex- 

 ture. Its constituents are 



1 atom muriatic acid 4-625 



1 atom alumina 2-250 



3 atoms water 3-3.75 



10-25 



This salt cannot be converted into a chloride of 

 aluminum by heat ; when we make the experi- 

 ment, not only the water, but the whole of the 

 acid is driven off, leaving the alumina behind in 



