hy the Action of Hydrochloric Acid. 



3T1 



ing this salt with potassium hydroxide and evaporating to 

 expel ammonia, was boiled in a Bunsen distillation apparatus 

 with concentrated hydrochloric acid. The solution, at first 

 yellow, became green on long boiling. .In some cases ebullition 

 was kept up for 15 minutes. In working with amounts of 

 material represented by 0-0585 grm., or O'llTl grm. of T^Oj 

 Holverscheit obtained from about 28 per cent to 39 per cent, 

 or in the average about a third of the theoretical reduction, 

 and, while noting the fact that by working with wholly con- 

 centrated ("ganz. konz. HCl ") Rosenheim doubled this yield, 

 ventures the opinion that it is scarcely conceivable that Gibbs 

 obtained by boiling vanadic acid with hydrochloric acid and 

 estimating the chlorine liberated, results even approximating 

 the truth. 



The green color of Holverscheit's residual solution shows, of 

 course, an incomplete reduction — the consequence of the use 

 of an acid which, as intimated, was not of full strength. Ros- 



enheim, however, got the blue residual solutions characteristic 

 of the condition of oxidation corresponding to VoO^. Why 

 the deticiency in the chlorine indicated in the receiver in RovS- 

 enheim's experiments was so marked is not obvious, unless it 

 be supposed that chlorine was lost from the apparatus in the 

 sudden evolution which takes place when action begins. Our 

 experience, moreover, shows that the liberation of chlorine 

 begins as soon as the hydrochloric acid and vanadic acid come 

 into contact. In our experiments upon the process, therefore, 

 we have used a form of apparatus, shown in the accompanying 

 figure, such that no chlorine can be evolved before the appa- 

 ratus is connected and ready. For the retort we have used a 

 Yoit flask upon the inlet tube of which was sealed a stoppered 

 funnel, while the outlet tube was sealed to a Drexel wash- 

 bottle and this in turn was joined to Will and Yarrentrapp 

 bulbs. The Drexel bottle and bulbs used as receiver and trap 



