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INDIANA UNIVEESITY 



The advantages of this method are that the manipulation is com- 

 paratively simple and that the results of a given experiment may 

 be determined within a short time after its completion. 



The standard method for the determination of selenium — reduc- 

 ing selenium from the selenic to the selenious condition by heating 

 with hydrochloric acid and precipitating the metallic selenium with 

 sulphur dioxide, filtering and weighing — was used in a few experi- 

 ments as a check to show that the new method of calculating 

 yields was introducing no error into the work. The following table 

 contains the results obtained by the two methods : 



No. of Titration Reduction of 



Sample.^" Metiiod. Se Method. Difference. 



I. 72.91 per cent. 72.86 per cent. 0.052 per cent. 



II. 83.33 per cent. 83.30 per cent. 0.030 per cent. 



III. 96.03 per cent. 95.99 per cent. 0.040 per cent. 



The differences shown by the above table are negligible and within 

 the limits of experimental error. 



EXPERIMENTAL DATA. 



Results with Barium Selenate: Assuming the reaction 



BaSeO^ x (NHJ XO, = BaCOo x (NHJoSeO, 



one gram of barium selenate is equivalent to 0.344 gram ''ammo- 

 nium carbonate." An analysis of the "ammonium carbonate" 

 showed that it contained only 62 per cent as much carbon dioxide 

 as is contained in the body of the composition (NH^)oC03. This 

 analysis of the ''ammonium carbonate" was not made until near 

 the close of the research, which accounts for the fractional equiva- 

 lent molecules of carbonate used in the tables. 



In the following tables 0.7 gram of "ammonium carbonate" 

 represents 1.24 molecules of carbon dioxide to one molecule of ba- 

 rium selenate, 1.48 grams of "?t,mmonium carbonate" equal 2.48 

 molecules and 2.8 grams equal 4.96 molecules of carbon dioxide to 

 one molecule of barium selenate. 



Nos. I and II a^ e results obtained from barium selenate and No. Ill with lead 

 selenate. 



