HYDRATES AND CARBONATES OF THE ALKALI-METALS, ETC. 431 



corresponding to the formula Li 2 + 0*004 Li 2 C0 3 , and showing that the preparation was 

 a fair approximation to pure monoxide of lithium. 



In regard to the properties of this oxide, I have nothing to add to what I have stated 

 incidentally, except that it acts only sluggishly on water with apparently little evolution 

 of heat. An exact determination of the heat- evolution by means of a Bunsen calorimeter, 

 and experiments on the action of the oxide on alcohol, are contemplated. 



Hydrate of Lithia. 



This, according to my original programme, was to have been produced from the oxide 

 by means of water ; but the preparation of the latter having proved so very wasteful of 

 time, I fell back upon the old method of decomposing the sulphate with baryta- 

 water. 



160 grm. of Erfurt lithium carbonicum purissimum were dissolved in water, with 

 addition of a slight excess of sulphuric acid ; the dissolved carbonic acid was expelled by 

 heating, the surplus acid neutralised by addition of more carbonate, and the liquid 

 filtered. On the other hand, an almost saturated baryta-water was prepared from pure 

 crystals. 



Duplicate analyses of the two solutions showed that 1 grm. of sulphate of baryta 

 was obtained (by addition of sulphuric acid and chloride of barium respectively) from 

 25*109 grm. of the baryta-water, and from 3*8983 grm. of the lithia solution. Hence 

 1 grm. of the lithium solution should demand 6*4412 grm. of the baryta- water. But 

 a preliminary synthetical trial, made with 10 grm. of the lithia solution, showed that 

 64*6 grm. of the baryta water were just, but barely, sufficient to bring down the whole 

 of the S0 3 . Hence, in the actual preparation, the reagents were mixed in this latter 

 proportion (in the cold), and allowed to stand in well-stoppered bottles until the 

 precipitate of sulphate of baryta had settled completely. The supernatant liquors were 

 then syphoned off, the precipitates mixed with boiled-out water, again allowed to settle, 

 and the clear washings united with the first decantates, which, of course, had meanwhile 

 been preserved in well-stoppered bottles. 



The united leys (which amounted to about 15 litres, and, by calculation, should have 

 contained 58*77 grm. of Li 2 0) were boiled down as quickly as possible in a nickelled iron 

 basin (as made in Iserlohn for culinary purposes) to about 1 litre, care being taken to 

 keep the basin almost wholly covered with its lid during the evaporation, so as to leave 

 only a small outlet for the steam. The concentrated liquor was then transferred to a 

 bottle provided with a glass stopper, and next tested for S0 3 and BaO, when a trace of 

 the former was found to be present. A small quantity of baryta water therefore was 

 added, and the minute precipitate of sulphate of baryta allowed to settle. The clear 

 liquor was now found to contain a very minute trace of baryta, which however was 

 allowed to remain. 



The clear liquor was syphoned off and boiled down in a platinum basin (which was 



