MOLYBDENUM. 253 



lybclenum by two methods. First, the carefully purified trioxide, in 

 weighed amounts, was dissolved in an excess of a standard solution of 

 caustic soda. This solution was standardized by means of hydrochloric 

 acid, which in turn had been standardized gravimetrically as silver 

 chloride. Hence, indirectly, the ratio 2AgCl : MoO., was measured. Sul- 

 phuric acid and lime water were also used in the titrations, so that the 

 entire process was rather complicated. Ignoring the intermediate data, 

 the end results, in weights of M0O3 and AgCl, were as follows. The third 

 column gives the M0O3 proportional to 100 parts of AgCl : 



3.6002 

 3-5925 

 3.73" 

 3.8668 

 3-9361 

 3.8986 

 39630 

 3-9554 

 3-9147 

 3-8543 

 3-9367 



.0018 



The second method adopted by Seubert and Pollard was the old one 

 of reducing the trioxide to metal by heating in a current of hydrogen. 

 The weights and percentages of metal are subjoined : 



MoO^. Mo. Per cent. 



1.8033 I. 2021 66.661 



1.9345 I. 1564 66.670 



3.9413 2.6275 66.666 



1.524 1 1. 0160 66.662 



4.0533 2.7027 66.679 



Mean, 66.668, =b .0022 



This mean may be combined with the results of previous investigators, 

 thus : 



Dumas 66.649, ± .0300 



Debray 66.556, db .0200 



Rammelsberg 66.708, ± .0680 



Seubert and Pollard 66.668, zh .0022 



General mean . 66.665, i 0022 



Here the data of Seubert and Pollard alone exert any appreciable 

 influence. 



Neglecting all determinations made previous to 1859, there are now 



