460 A. L. Day and J. K. Clement — Gas Thermometer. 



This is closed by a glass stopper in which are sealed a small 

 g]ass tube passing to the bottom of the flask and serving to 

 fill the flask with hydrogen and to replace the gases formed 

 in the experiment ; a dropping funnel through which the acid 

 used to dissolve the zinc is introduced, and lastly, an upright 

 outlet tube surrounded by a small condenser. The outlet was 

 connected with a wash bottle containing a solution of silver 

 nitrate. As pure zinc dissolves with difficulty in dilute 

 hydrochloric acid, the metal was reduced to the form of 

 shavings by the aid of a lathe. Fifty grams of these shavings 

 were introduced into the flask, the air in which was at once 

 replaced by hydrogen. Dilute hydrochloric acid was then let 



Analysis of Zinc. 



As None found 



Sb -002 



Sn Not looked f or 



Au ._ 



Pt 



Ag _. None 



Bi 



Pb ._. - "051 



Cd -004 



Ni None 



Co " 



Fe -006 



Si _-. None 



S " 



•063 



in through the dropping funnel. The solution was facilitated 

 by warming. At the end of the operation, the gas in the 

 flask was driven out by pure hydrogen. The silver nitrate 

 solution which contained a black precipitate was then filtered. 

 The antimony in the precipitate was determined by dissolving 

 it in nitric acid with the addition of a little tartaric acid, 

 precipitating the silver with hydrochloric acid, evaporating 

 the filtrate to dryness on the steam bath and precipitating 

 by hydrogen sulphide. The precipitate was dissolved in 

 a few drops of ammonium sulphide, the solution filtered into 

 a small tared porcelain capsule, evaporated, decomposed by 

 nitric acid and weighed as Sb 2 4 . After separating the silver 

 from the first filtrate which contained the arsenic, it was 

 evaporated to dryness, reduced with sulphurous acid and 

 precipitated by hydrogen sulphide. None was detected with 

 certainty. 



If this solution had been tested by Marsh's method, no 

 doubt a trace would have been found, but as its quantity was 

 of a different order of magnitude from the other impurities it 

 was not thought worth while to make the test. Gunther deter- 



