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



reagent proved the contrary. The silver solution was now 

 diluted to several liters and precipitated with hydrochloric 

 acid. The filtrate was evaporated in porcelain to a small 

 volume and in this the remaining impurities were sought for 

 by well-known methods. Only lead and iron and the merest 

 trace of copper were found. A blank determination was made 

 for iron. Found in the silver -f reagents, *0013 per cent ; in 

 the reagents, '0002 per cent; leaving *0011 per cent in the 

 silver. 



For the estimation of sulphur, a separate portion of 38 

 grams was taken, the silver was removed in the same manner, 

 and the filtrate evaporated to dryness in porcelain. The 

 small residue was then evaporated again with hydrochloric 

 acid to decompose nitrates. The final residue was dissolved 

 in a small volume of water acidulated with hydrochloric acid, 

 filtered to remove any silver chloride which might have escaped 

 precipitation and precipitated with barium chloride. Found 

 l*4 rag BaS0 4 , while the same quantity of reagents gave 0*4 mg 

 BaS0 4 : S = '0004 per cent. 



Analysis of Silver. 



As _ . none 



Sb " 



Sr « 



Au -0005 



Pt -0001 



Cu merest trace 



Bi none 



Pb -0008 



Hg . _ none 



Cd " 



Zn « 



Ni ' " 



Co " 



Fe -0011 



S -0004 



C . -0003 



■0032 



The Copper. — The copper was of the form known as " cop- 

 per drops cooled in hydrogen " and was obtained from Eimer 

 and Amend of New York. Not all copper of this brand is 

 equally pure. The sample analyzed was a portion of a 25 lb. 

 lot. The method followed in the analysis was essentially that 

 of Hampe,"* in which the copper is separated from the impuri- 

 ties by precipitation as cuprous thiocyanate. A 100-gram por- 

 * Lunge, Chem.- tech. Methoden, ii, 202. Chem. Ztg. 1691, 1893. 





