382 IRON, NICKEL, COBALT, c . 



barytes. From this experiment it follows, that 

 15*625 grains of protosulphate of cerium con- 

 tain 5 grains of sulphuric acid. 



3. 15-625 grains of the crystals of protosul- 

 phate of cerium, were exposed for an hour on 

 the sand bath to a heat of about 500 or rather 

 more. The loss of weight was 3*125 grains ; 

 and this loss was not increased though the heat 

 was continued for twenty four hours. The salt 

 thus treated, had become white. It still red- 

 dened vegetable blues, and was completely solu- 

 ble in water. Hence, the loss of weight must 

 be ascribed to the escape of water. Now, the 

 weight of three atoms of water is equivalent to 

 3'375 grains. This exceeds the loss of weight, 

 actually sustained by the salt, by 0-25 grains, 

 equivalent to Jzrth of an atom. The salt being 

 as neutral as possible, and 15*625 grains of it 

 containing 5 grains of sulphuric acid, which is 

 equivalent to an atom, the same weight of salt 

 must contain a determinate number of atoms of 

 water ; and it is obvious, that the true quanti- 

 ty of water must be 3 atoms, or 3-375 grains. 

 I found that the salt could not be rendered per- 

 fectly anhydrous without at the same time losing 

 a portion of its acid. 



4. Five sulphuric acid, and 3*375 water added 

 together make 8*375, which being subtracted 

 from 15*625, the total quantity of salt used, 

 leaves 7*25, which must represent the weight of 



