OF ARTS AND SCIENCES. 21 



It has long been known that the vapor from a boiling solution of 

 antimony in hydrochloric acid carries off a portion of the chloride of 

 antimony. We have found that this is true only when the solution is 

 quite concentrated : that the amount which escapes rapidly diminishes 

 as the solution is diluted, and that it soon becomes wholly imper- 

 ceptible. Still, as in our experiments the boiling was frequently greatly 

 prolonged, we guarded against any loss from this cause by using 

 the reversed condenser, as above described. The time required for the 

 reduction varied very greatly under different conditions. It was seldom 

 finished in less than an hour, and the process frequently required 

 several hours. The boiling was stopped as soon as. the pale color of 

 the solution was perfectly discharged ; but, while the flask was cooling, 

 the current of carbonic dioxide was steadily maintained. When cold, a 

 measured portion of a concentrated solution of tartaric acid (containing 

 generally from ten to fifteen grammes of the crystallized acid) was 

 added to the flask, and the contents were then at once transferred to the 

 large Erlenmeyer flask in which the antimony was to be precipitated. 

 The transfer was accomplished very easily and perfectly in the follow- 

 ing way. 



Into the Erlenmeyer flask was first poured about 500 cubic centi- 

 metres of water strongly charged with carbonic dioxide; and then the 

 platinum tunnel, on which, as we have stated, the antimony bullets had 

 been weighed, and which had been carefully protected meanwhile, was 

 placed in the mouth of the large flask. As the solution was now poured 

 in from the smaller vessel, the bullets were of course caught by the 

 tunnel, and the aerated wash water, which also passed through the 

 tunnel, served to wash the bullets as well as the glass. The tunnel 

 and its contents were then dried and weighed, and the loss from the 

 previous weight gave accurately the amount of additional metal 

 which had passed into solution during the process of reduction. 

 It will be noticed that, during the whole process, the balls were never 

 touched with the fingers, or brought in contact with any object by 

 which their weight could be in the least altered. It was found how- 

 ever, to be essential to the success of the method that not more than a 

 few decigrammes of metal, at most, should be dissolved from the balls ; 

 for, otherwise, the surfaces became disintegrated, and liable to abrasion. 

 Hence, the objection to using an excess of nitric acid in dissolving the 

 original quantity of antimony. 



The precautions here described may seem unnecessary to those who 

 are not familiar with the fact that a solution of antimony in hydrochloric 

 acid oxidizes with very great rapidity in the air, — fully as ra[)idly as the 



