TUNGSTEN. 149 



composed by nitric acid, and the silver thus taken into solu- 

 tion Avas titrated Avith standard sodium chloride. In three 

 others the tungstate was treated directly with common salt, 

 and the residual silver chloride collected and weighed. 

 Here again, on account of some complexity in Zettnow's 

 figures, I am compelled to reduce his data to a common 

 standard. To 100 parts of AgCl the following quantities of 

 AgjWO^ correspond : 



By First Method. 

 161.665 

 161.603 



Mean, 161.634, ± .021 



; By Second Method. 



^ 161.687 



161. 651 

 161. 613 



Mean, 161.650, ± .014 

 General mean from both series, 161.645, =^ -C^ 



Finally, we have two analyses by Roscoe of tungsten hex- 

 chloride, published in the same paper with his results upon 

 the trioxide. In one experiment the chlorine was deter- 

 mined as AgCl ; in the other the chloride was reduced by 

 hydrogen, and the residual tungsten estimated. By bring- 

 ing both results into one form of expression we have for the 

 percentage of chlorine in WClg : * 



53-5S8 

 53-632 



Mean, 53.610, dr .015 



We have now five ratios from which to calculate the 

 atomic weight of tungsten : 



(l.) Percentage of W in WOg, 79.3215, ± .00085 



(2.) Percentage of H^O in BaO.4WO3.9H2O, 13.0368, =b .0060 



* The actual figures are as follows : 



19.5700 grm. WClg gave 42.4127 grm. AgCl. 

 10.4326 " 4.8374 " tungsten. 



