330 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



troduced into the flask, which is then connected with the condenser. 

 Under the adapter is placed a small flask containing 25 c.c. concen- 

 trated nitric acid, which should just cover the end of the adapter. 

 There are then added, through a long funnel tube, 100 c.c cool, con- 



PlGURE A. 



centrated hydrochloric acid, in which the amount of arsenic is as small 

 as possible and accurately determined. The stopper of the flask is at 

 once inserted. 



Distillation is begun with a low flame and is continued at such a 

 rate that the volume of the liquid in the flask is reduced to about half 

 in the course of thirty to forty minutes. Repeated trials have shown 

 that all the arsenic, in the quantities for which this method is intended, 

 goes over by this operation, whether the arsenic is present as arsenious 

 or arsenic acid. As by far the greater part of the arsenic goes over 



