OF ARTS AND SCIENCES. 9 



I have already stated, that in repeated trials I had not been able to 

 obtain the sodic ditungstate described and analyzed by Lefort, though 

 the process given by him was followed implicitly. In one experiment 

 the crystals obtained gave on analysis results which correspond closely 



with the formula 



12W0 8 .5Na 2 + 28aq. 



1.9868 gr. lost on ignition 0.2786 gr. water = 14.02% 



1.2870 gr. " " 0.1806 gr. " =14.01% 



0.9365 gr. gave 0.7243 gr. W0 3 = 77.34% 



1.3560 gr. " 1.0483 gr. " =77.31^ 



Found. 



77.34 77.31 



8.66 

 14.02 14.01 

 100.00 



In this experiment the normal tungstate was dissolved in cold water 

 to a very strong solution, glacial acetic acid was added in excess, and 

 the whole allowed to stand for twenty-four hours, when prismatic 

 crystals separated. In a second experiment a concentrated solution of 

 sodic tungstate was heated to the boiling point and ordinary acetic acid 

 added in excess. Alcohol then threw down a pasty mass, which, after 

 re-solution in water and crystallization, gave on analysis results which 

 corresponded with the formula 



22W0 3 . 9Na 2 0-f 51 aq. 



The small differences between the calculated formula and the direct 

 results of the analyses, in this instance, are exactly such as would be 

 produced by the admixture of a small percentage of the 10:4 sodium 

 salt, which, as I have shown above, is formed when a solution of neutral 

 6odic tungstate is boiled for some time with an excess of acetic acid. 



