OP ARTS AND SCIENCES. 119 



lution containing sodic tungstate and phosphate, in which the propor- 

 tion of the latter to that of the former is as 1 to 12, or as 1 to any 

 number less than 12. In other words, it appears to be the limiting 

 term of all the series. When the salt is fused with sodic carbonate, 

 carbonic dioxide is given off, but not in the proportion which might 

 be expected. In one experiment, 



2.2298 gr. lost 0.5408 gr. CO., and H 2 = 16.94% 



1.2621 gr. lost on simple ignition 0.0922 gr. H 2 = 7.31% 



The ratio of the W0 3 in the salt to the C0 2 expelled is here as 

 38 : 22, or very nearly as 24 : 13. If the ratio were as 24 : 13, the 

 reaction would be represented by the equation 



24 W0 3 . P 2 5 . 2 Na 2 -j- 13 C0 3 Na 2 = 12 (2 W0 3 . Na 2 0) + 

 P 2 5 . 3 Na 2 0. 



A small proportion of neutral tungstate, W0 4 Na 2 , is probably formed 

 by the further action of the acid tungstate on the alkaline car- 

 bonate. 



The 24 : 2 acid sodium salt gives no precipitate with the sulphates 

 of zinc, manganese, and copper; a white crystalline precipitate with 

 argentic nitrate, and after a short time with baric chloride and amnio- 

 nic nitrate ; no precipitates with calcic and strontic chlorides, but after 

 a short time scanty crystalline salts. 



The 24 : 2 acid salt is the only sodium compound of the 24-atom 

 series which I have been able to prepare. When a solution of this 

 salt is carefully neutralized with sodic carbonate, the 6-atom or fully 

 saturated salt, 24 W0 3 . P 2 5 . 6 Na 2 0, possibly exists in the solu- 

 tion, but a definite salt could not be obtained by evaporation. When 

 neutral sodic tungstate and hydrodisodic phosphate are mixed in the 

 proportion of 24 : 2, and acetic acid is added to the solution after 

 boiling for some time, no precipitate is formed, but alcohol throws down 

 a colorless oil which soon solidifies to a white gummy mass. I did 

 not obtain a crystalline well-defined salt from this by re-solution and 

 evaporation, but others may perhaps be more successful. 



When a sufficient quantity of sodic carbonate is added to a solution 

 of the acid sodic phospho-tungstate, a mixture of sodic tungstate and 

 sodic phosphate appears to be formed. 



24 W0 3 . P 2 O s . 2 Na 2 + 25 C0 3 Na 2 = 24 (W0 3 . Na 2 0) + 

 P 2 5 . 3 Na 2 0. 



The phospho-tungstate is formed again on adding an excess of acid. 



