( 429 ) 



XII. — On the Behaviour of the Hydrates and Carbonates of the Alkali-Metals, and of 

 Barium, at High Temperatures, and on the Properties of Lithia and, the 

 Atomic Weight of Lithium. By Professor W. Dittmar. 



(Read 17th June 1889.) 



The fragmentary nature of our knowledge of the behaviour of the more strongly 

 basilous hydrates and carbonates at high temperatures is owing chiefly to the absence of 

 a suitable material for the necessary crucibles. Unfortunately there is no metal which 

 combines the infusibility of platinum with the chemical inertness of gold, in opposition to 

 fiery-fluid caustic alkalies. But the corrosive action of these on platinum, as I showed 

 some years ago,* is a function only of the peroxides formed from them by the action of 

 atmospheric oxygen, and, consequently, can easily be prevented by operating in an 

 atmosphere of hydrogen or nitrogen. 



This observation forms the basis of the experimental methods used in the present 

 research. Before commencing my report, however, I should wish to give myself the 

 pleasure of acknowledging that almost all the laboratory work involved was done by my 

 private assistant, Mr Eobert Anderson, and of expressing my indebtedness to him for 

 the excellent manner in which he carried out my directions. 



Lithia. 



Having, in the course of my earlier research,t found that carbonate of lithia, if kept 

 at a bright red heat in an atmosphere of hydrogen, loses carbonic acid very largely, I 

 some time ago repeated the experiment, with the view primarily of seeing whether it is 

 possible in this manner to obtain the pure oxide, Li 2 0, of which the handbooks of chemistry 

 tell us so very little, and, in the case of success, utilising it as a starting-point for the 

 preparation of the hydrate, of the properties of which we are almost equally ignorant. 

 The experiment, as I may state at once, proved a success. 



The material which I started with this time was a supply of lithium carbonicum 

 purissimum, from Trommsdorff of Erfurt, which, according to an analysis by Mr Robson, 

 had the following composition : — 



Lithia, Li 2 0, ..... 

 Soda, Na 2 0, ..... 

 Potash, K 2 0, ..... 

 Magnesia, MgO, .... 



Carbonic acid, C0 2 , . 

 Sulphuric acid, S0 3 , 



VOL. XXXV. PART II. (NO. 12). 



40-14 : 



: 30-04 



= 



1-3362 



0-03 : 



: 62 



= 



0-0005 



0-07 



: 94 



= 



0-00074 



012 : 



:40 





0-0030 





1-34044 



59-32 



:44 



= 



1-3482 



0-09 



: 80 





o-oon 



99-77 



1-3493 



m. Industry for 1884, 



page 303. 



t Ibid. 









4 C 



