20 P. T. Cleve, 



0.6213 gram was fused with a mixture of carbonate of sodium and 

 potassium and the fused mass treated with water. The solution, filtered 

 from insoluble residue, gave 0.5236 gram Mg2P207. The insoluble re- 

 sidue was dissolved in nitric acid and the did3niiium precipitated with 

 oxalic acid. The DigOa obtained by ignition of the oxalate weighed 

 0.1991 gram. The filtrate from the oxalate of did3anium gave 0.1364 

 gram MgaPaO,, the total MgaPgOi being therefore 0.6600 gram. 



0.4038 gram gave 0.1284 gram DigOa. 

 In percent: 



Calc 



DijOa 32.05 31.80 166 31.86 



P^Oj 67.95 — 355 68.14 



100.00 521 100.00 



Spec. Grav: 



1.2324 gram, t" 18«.4 sp. Gr. 3.333 

 1.8311 » » » » y> 3.358 



Mean of both determinations: 3.345. 

 Molecular volume: 155.8. 



Carbonate of didymium 



DisSCO^ + SH^O. 



A vessel in which some basic nitrate of didj'mium was suspended 

 in a solution of nitrate of didymium, containing some nitrate of ammonium, 

 was left for several months exposed to the air at a temperature from 

 10° — 15^ By this time tolerably large tabular crj^stals (4 to 5 millim. 

 in diameter) and scales of nacreous lustre and violet colour had been 

 deposited. They were washed free from the basic nitrate and were 

 found to consist of carbonate of didymium. 



0.4274 gram, pressed between filter-paper, were heated and left 

 0.2331 gram DijOg. 



0.5033 gram were heated together with bichromate of potash in a 

 current of dry air and gave 0.1194 gram HjO and 0.1083 gram CO2. 



