HYDRATES AND CARBONATES OF THE ALKALI-METALS, ETC. 



433 



Hence by the means — 





* Lithia as hydrate, ...... 



. 33-48 



Lithia as carbonate, ...... 



0-62 



Carbonic acid in the carbonate, .... 



0-91 



Baryta, ........ 



0-08 



* Water, by difference, ..... 



. 64-91 



3410 



100-00 

 * Corresponding to the formula Li 2 + 3-2347 H 2 0, or LiOH+ 1-1173 H 2 or rather LiOH.H 2 + 0-1173 x H 2 of 

 surplus water. 



2 - 66 7 grm. of the crystals were placed in the gas crucible, and heated in a current of 



hydrogen, first gently and then over the gas blowpipe. After four hours' heating the weight 



of the residue became constant at 0*901 grm. = 3378 per cent, of the weight of the original 



substance, which comes very near the 34'10 per cent, of Li 2 found in the analysis. To 



confirm this result (which surprised me, because at the time I shared the general 



impression amongst chemists that even hydrate of baryta, BaO.H 2 0, is stable at a red 



heat) weighed quantities of the residue were converted into neutral sulphate and the 



latter weighed. Kesults — 



(1) (2) 



Substance analysed, . .... 0418 0*294 grm. 



Sulphate obtained, ..... 1-531 L075 „ 



Percentage of Li 2 0, .... 99-96 99-80 



The residue undoubtedly was anhydrous lithia. 



Mr Anderson's experiments on the behaviour of lithia-crystals at lower temperatures 

 may be passed over because this subject was at a later date worked out more completely 

 by Mr Henderson, who, however, had to make fresh lithia-crystals for his purpose, Mi- 

 Anderson's stock having been entirely used, up in the solubility experiments, which I 

 shall report on presently. A crop of crystals, corresponding to Mr Anderson's No. 2, was 

 operated upon. 



For the determination of the crystal water, a known weight of crystals contained in a 

 platinum boat was placed in a combustion tube surrounded by a square air-bath made 

 of asbestos pasteboard, and in this condition kept at the fixed-upon temperature while 

 a current of pure and dry hydrogen was passing through the tube. In each of the two 

 experiments which were made we began by maintaining a temperature of 100° until the 

 weight of the residue was constant. The residue was then exposed to a succession of 

 higher temperatures for the times stated, and after each such period of heating the weight 

 of the residue noted. 



Experiment I. — Weight of crystals taken = 1*1720 grm. Constant weight at 100° = 



0*6584 grm. ; hence loss = 0*5136. The weights of the successive higher temperatures 



was as follows : — 



After 40 minutes at 120° 0-6590 



150° 0-6598 



170° 0-6604 



200° 0-6602 



