HYDBATES AND CARBONATES OF THE ALKALI-METALS, ETC. 439 



sulphate. In two experiments (which happened to agree absolutely) the percentage of 

 Li 2 in the saturated solution was found to be 0'59. 



Experiments on the action of alcohol on the anhydrous oxide are in preparation. 



Before passing on I may say that a series of attempts to produce a peroxide of 

 lithium from its oxide or carbonate failed. That metallic lithium when kindled in 

 oxygen burns into chiefly peroxide is, I believe, ascertained. 



Knowing that fused carbonate of lithia at a red heat and in the presence of air 

 attacks platinum crucibles very badly, I fully expected that oxide of lithium would 

 unite readily with oxygen also in the absence of platinum. 



Other Hydrates. 



I. Baryta. — When I had found to my surprise that hydrate of lithia, when heated 

 in hydrogen, is so readily reduced to oxide, I at once caused Mr Hodge to see how 

 baryta-crystals behave under the same circumstances, and, as a necessary preliminary, to 

 prepare carbonate-free crystals by dissolving a quantity of Erfurt "Purissimum" in 

 boiling water, filtering the solution into a flask, allowing to cool, collecting the crystals 

 which separated out on cooling on a funnel, and sucking them dry in a current of 

 carbonic-acid-free air. The crystals were then more fully dried under a bell jar over 

 solid caustic soda. 



A small quantity of them was placed in the "hydrogen-crucible," and therein exposed, 

 in a current of hydrogen, first to lower temperatures and lastly to the full heat of a gas 

 blowpipe. In the first experiment, the heating, after establishment of the highest 

 temperature, was continued for two hours. The residue was then analysed by treating 

 a known weight with water and then converting it into sulphate by evaporation 

 with sulphuric acid. 0726 grm. of substance gave 1'068 grm. of BaS0 4 = 0*70148 of 

 BaO = 96*62 per cent, of BaO. In the second experiment about 10 grm. of crystals were 

 used, and the heating continued, until the weight of the residue became constant, which 

 took about four hours. The residue looked like anhydrous baryta, and 0*342 grm. of it, 

 when dissolved in water, and precipitated with sulphuric acid, yielded 0*5225 grm. of 

 BaS0 4 , corresponding to 100*35 per cent, of BaO. 



These results of Mr Hodge's were subsequently confirmed by Mr Anderson, who 

 besides extended the inquiry to the carbonate. 



1. About 2 grm. of baryta-crystals were heated in hydrogen over (ultimately) the 

 blowpipe for an hour, and the residue was weighed; the heating was then resumed 

 and continued for other thirty minutes, which, however, reduced the weight by only 

 1 mgrm. 0*928 grm. of the product, when dissolved in water and hydrochloric acid, 

 in a Classen apparatus, gave off 1 mgrm. of C0 2 = 0*108 per cent. The solution gave 

 1*4096 grm. of BaS0 4 = 99*76 per cent, of BaO. 



(In regard to Carbonate of Baryta see below under "Carbonates.") 



After these results with the hydrates of lithia and baryta I was quite prepared to 



