272 A GENERAL FORMULA FOR THE 



To apply this method, then, to the present formula ; add to 

 the clear liquor poured off after the precipitation of the oxa- 

 late of lime, heated to 100°, and, if necessary, reduced by eva- 

 poration, a solution of carbonate of ammonia; and immediate- 

 ly drop in a strong solution of phosphoric acid, or phosphate 

 of ammonia, continuing this addition with fresh portions, if 

 necessary, of carbonate of ammonia, so as to preserve an ex- 

 cess of ammonia in the liquor as long as any precipitation is 

 produced. Let the precipitate be washed ; when dried by a heat 

 not exceeding 100°, it is the phosphate of ammonia and mag- 

 nesia containing .019 of this earth ; but it is better for the sake 

 of accuracy, to convert it into phosphate of magnesia by calci- 

 nation for an hour at a red heat : 100 grains, then, contain 40 

 of magnesia. 



Evaporate the liquor remaining after, the preceding opera- 

 tions to dryness, and expose the dry ■ mass to heat as long as 

 any vapours exhale, raising it towards the end to redness. 

 The residual matter is muriate of soda, 100 grains of which 

 are equivalent to 53.3 of soda, and 46.7 of muriatic acid. It is 

 not, however, to be considered necessarily as the quantity of 

 muriate of soda contained in the water ; for a portion of soda 

 may have been present above that combined with muriatic 

 acid, united, for example, with portions of sulphuric or carbo- 

 nic acid ; and, from the nature of the analysis, this, in the pro- 

 gress of it, or rather in the first step, that of the removal of 

 these acids by the muriate of barytes, would be combined with 

 muriatic acid. It does not, therefore, give the original quan- 

 tity of that acid ; but it gives the quantity of Soda, since no 

 portion of this base has been abstracted, and none introdu- 

 ced. 



The quantity of muriatic acid may have been either greater 

 or less than that in the muriate of soda obtained. If the quan- 

 tity 



