144 THE ATOMIC WEIGHTS. 



Next in order of time comes the work of Schneider,* who, 

 with characteristic carefulness, took every precaution to get 

 pure material. His percentages of tungsten are as follows : 



Reduction Series. 

 79-336 

 79-254 

 79-312 

 79.326 

 79-350 



Mean, 79.3156, zfc 



Oxidation Series. 

 79.329 



79-324 

 79.328 



Mean, 79.327, ± .0010 



Closely agreeing with these figures are those of Marchand."^ 

 published in the following year : 



Reditction Series. 



79-307 

 79.302 



Mean, 79.3045, .0017 



Oxidation Series. 

 79-321 

 79-352 



Mean, 79.3365, ± .0105 



The figures obtained by v. Borch| agree in mean tolerably 

 well with the foregoing. They are as follows : 



Redtiction Series. 

 79.310 

 79.212 

 79.289 



79-313 

 79.225 

 79.290 

 79.302 



Mean, 79.277, ± .0106 



* Journ. fiir Prakt. Chem., 50, 152. 1850. 

 t Ann. Chem. Pharm., 77, 261. 1851. 

 J Journ. fiir Prakt. Chem., 54, 254. 1851. 



