324 Mr. Maddrell on the Metaphosphates. 



Found. 

 Reckoned. Atom. I. II. 



16-368 = 3 MgO 10-276 16-12 



75-376 = 4 PO5 75-250 



8-256 = NaO 8-146 



100-000 99-672 



Formula, 3 (MgO, PO5) +NaO, PO5. 



The different result obtained by Professor Gregory no doubt 

 arose from the method upon which his examination of this 

 salt was conducted, viz. by determining the amount of mag- 

 nesia pi-esent, and considering the loss on the weight of sub- 

 stance used to represent phosphoric acid, and probably from 

 not thinking at the time of the presence of a salt of soda in 

 bones. 



With regard to the phosphoric acid prepared as above, after 

 the salt has ceased to form, I find that it is not yet quite pure, 

 but contains traces of magnesia as well as soda, and therefore 

 this process will always yield an acid containing more or less 

 of these substances. 



Under the impression that the phosphoric acid obtained 

 by this pi'ocess \Aas pure, I attempted to prepare with it the 

 metaphosphates of nickel and cobalt, by adding the sulphates 

 of these bases to an excess of the acid, and heating as before 

 to upwards of G00° F., with the idea that they might be de- 

 posited in a somewhat similar manner to the metaphosphatc 

 of magnesia. This I found on analysis not to be the case, as 

 the salts w'hich I obtained in this way were not the pure me- 

 taphosphates, but double salts in combination with soda, 

 closely allied in their composition to Gregory's salt. 



The nickel compound obtained in this way was deposited 

 in the form of a greenish-yellow, anhydrous powder, insoluble 

 in water and diluted acids, but soluble in concentrated sul- 

 phuric acid. 



The analysis of this salt was made by fusing with carbo- 

 nate of soda, and treating the fused mass with water to sepa- 

 rate the metallic oxide from the alkaline phosphate. A second 

 quantity was taken for the determination of soda, which I dis- 

 solved in concentrated sulphuric acid, then diluted with water, 

 and precipitated the solution containing phosphoric acid by 

 acetate of lead, and the excess of lead in the filtered solution 

 by sulphuretted hydrogen. To the filtered solution was then 

 added an excess of ammonia with sulphuret of ammonium to 

 precipitate the nickel, and the solution containing soda was 

 evaporated and detei'mined as a sulphate. 



