430 PROFESSOR W. DITTMAR ON THE BEHAVIOUR OF THE 



The preparation, certainly, is not chemically pure ; yet I accepted it as sufficiently 

 pure for my purposes.* 



As the preparation is very bulky, I began by fusing successive instalments in a 

 platinum crucible (in hydrogen) to produce some 26 grammes of an anhydrous and 

 partly causticised compact substance. The crucible used for this, and in the subsequent 

 heatings, was the same as I had employed in my previous research, — an ordinarily shaped 

 platinum crucible of about 30 c.c. capacity, provided with a well-fitting overlapping lid, 

 bearing two autogynically soldered-in narrow platinum tubes, one for letting in the 

 hydrogen, the other for the escape of the volatile products. The inlet-tube projects into 

 the crucible to the extent of about 1 centimetre, the other commences at the lid. 



The fused preparation was found, in two analyses, to contain 42*19 and 42*12 

 per cent, of C0. 2 , instead of the 59*44 demanded by Li 2 C0 3 , if Li = 7'02; = 16. 

 15*41 grm. of this carbonate were placed in the crucible and heated repeatedly in a con- 

 tinuous current of purified dry hydrogen, for, in all, thirty-seven hours. At first a gas 

 blowpipe was used, but the constant working of the bellows proving tiresome, a simple 

 powerful " Bunsen " was substituted and employed for the greater part of the process, the 

 gas blowpipe being resumed only at the later stages. The total loss of weight amounted to 

 8*562 grm., including a not inconsiderable quantity of volatilised lithia, which comes off 

 more especially in the earlier stages of the process. The residual substance (6*849 grm.) 

 was a very hard stone-like mass, which, when broken up into fragments and again heated 

 in hydrogen, only sintered slightly, but did not fuse. It exhibited a slightly bluish tinge, 

 owing probably to the presence in it of a trace of sulphide. For the analysis of the 

 product a known weight of it was decomposed in a Classen apparatus (i.e., under an 

 inverted condenser) with dilute hydrochloric acid, and the small quantity of C0 2 which 

 came off, after having passed a chloride of calcium tube, collected in a tared soda-lime 

 tube and weighed. 



The chloride of lithium solution produced was evaporated with sulphuric acid to dryness, 

 the residue ignited, and these operations repeated until the sulphate was constant in 

 weight and its solution neutral to litmus ; it was then weighed as Li 2 S0 4 . Three such 

 analyses gave the following results : — 



(i) (2) (3) 



C0 2 . . . . 0-55 0*26 0-60 



Li 2 6 .... 99-60 99-57 not done. 



Adopted Numbers. 



C0 2 0-60 



Li 2 99-57 



100-17 



* In the research referred to I took special care to eliminate from my preparation every trace of potassium, 

 rubidium, and caesium. Yet, when fused in platinum at a red heat in the presence of air, it attacked the metal badly, 

 v. ith formation of a dark-coloured platinite. This is contrary to a statement of Troost's, who says (Victionnaire de 

 Clrimie, vol. ii. part i. page 228), that " lithia" attacks platinum only if contaminated with rubidium or coesium. 



