LITHIUM. 85 



nizable by spectral analysis, and which accounted for the error. In the 

 later paper Troost made use of the chloride and the carbonate of lithium, 

 both spectroscopically pure. The carbonate was strongly ignited with 

 pure quartz powder, thus losing carbon dioxide, which loss was easily 

 estimated. The subjoined results were obtained : 



.97ogrm. Li 2 CO 3 lost .577 grm. CO 2 . 59-485 per cent. 



1.782 " 1.059 " 59.427 " 



Mean, 59.456, .020 



The lithium chloride employed by Troost was heated in a stream of 

 dry hydrochloric acid gas, of which the excess, after cooling, was ex- 

 pelled by a current of dry air. The salt was weighed in the same tube 

 in which the foregoing operations had been performed, and the chlorine 

 was then estimated as silver chloride. The usual ratio between LiCl 

 and 100 parts of AgCl is given in the third column : 



1.309 grm. LiCl gave 4.420 grm. AgCl. 29 615 



2.750 " 9.300 " 29.570 



Mean, 29.5925, .0145 



This, combined with Mallet's mean, 29.581, .0087, gives a general 

 mean of 59.584, .0075. 



Next in order is the work of Stas,* which was executed with his usual 

 wonderful accuracy. In three titrations, in which all the weights were 

 reduced to a vacuum standard, the following quantities of LiCl balanced 

 100 parts of pure silver : 



39.356 



-39-357 



39-361 



Mean, 39.358, .001 



In a second series of experiments, intended for determining the atomic 

 weight of nitrogen, LiCl was converted into LiN0 3 . The method was 

 that employed for a similar purpose with the chlorides of sodium and 

 of potassium. One hundred parts of LiCl gave of LiN0 3 : 



162.588 

 162.600 

 162.598 



Mean, 162.5953, dr .0025 



The determinations of Dittmarf resemble those of Diehl; but the 

 lithium carbonate used was dehydrated by fusion in an atmosphere of 

 carbon dioxide. The carbonate was treated with sulphuric acid, and 



* Aroiistein's translation, 279-302. 



t Trans. Roy. Soc. Edinburgh, 35, II, 429. 1889. 



