262 THE ATOMIC WEIGHTS. 



For tungsten hexchloride we have two analyses by Roscoe, published 

 in the same paper with his results upon the trio'xide. In one experi- 

 ment the chlorine was determined as AgCl ; in the other the chloride 

 was reduced by hydrogen, and the residual tungsten estimated. By 

 bringing both results into one form of expression we have for the per- 

 centage of chlorine in WClg : * 



53.588 

 53-632 



Mean, 53.610, ± .015 



The work done by Smith and Desif probably ought to be considered 

 in connection with that of Pennington and Smith on the trioxide. 

 Smith and Desi started with tungsten trioxide, freed from molybdenum 

 by means of gaseous hydrochloric acid. This material was reduced in 

 a stream of carefully purified hydrogen, and the water formed was col- 

 lected in a calcium chloride tube and weighed. To the results found I 

 add the percentage of water obtained from 100 parts of WO3. Vacuum 

 weights are given. 



IFO,. 



.983024 



.99S424 

 1 .008074 



.911974 



•997974 

 1.007024 



Mean, 23.226, =t .oooS 



There are now six ratios from which to calculate the atomic weight of 

 tungsten : 



(I.) Percentage of W in WO3, 79.388, rt .00039 



(2.) Percentage of H^O in Ba0.4W03.9H.^O, 13.0368, ± .0060 



(3.) WO3 : 3H2O : : 100 : 23.226, ± .0008 



(4.) Am2Fe(SOj2.6H20 : FeWO^ : : .0365457, ± .0000012 : .0283549, zb .0000115 



(5.) 2AgCl : Ag2\VO^ : : 100 : 161.645, ± .012 



(6.) Percentage of CI in WClg, 53.610, zb .015 



These are reduced with — 



* The actual figures are as follows : 



19.5700 grm. WCle gave 42.4127 grm. AgCl. 



io.4.'?25 " 4-8374 grra. tungsten, 



t Read before .\nier. Philos. Soc, Nov. 2, 1894. 



