A. L. Day and J. K. Clement — Gas Thermometer. 459 



is dissolved in acidulated water and precipitated by barium 

 chloride. 



Found in 25 grams copper, 4-2 mg BaS0 4 



" " 75 cc nitric acid, 0*6 " 

 3-6 m s BaS0 4 = -002 per cent. 



Analysis of Copper. 



As none 



Sb " 



Sn " 



Se " 



Te " 



Au _. " 



Pt metals. -0011 



Ag -0007 and -0005* 



Bi none 



Pb 



Cd " 



Zn _ -0007 



Ni none 



Co " 



Fe -0038 



Si none 



S -0020 



•0083 



The Zinc. — This metal was obtained in the form of sticks 

 from the firm of Eimer and Amend. The method of Mylius 

 and Fromm was followed for the principal impurities.f 100 

 grams were dissolved in nitric acid. The solution was then 

 diluted and ammonia was added until the zinc at first precipi- 

 tated was entirely redissolved. Then enough hydrogen sul- 

 phide was added to throw down all the impurities of the 

 hydrogen sulphide and ammonium sulphide groups together 

 with considerable zinc. The precipitate was filtered off and 

 further separations were made as usual. 



The platinum metals and gold were not looked for as it was 

 thought quite improbable they would be present, but arsenic 

 and antimony were sought for by Gunther's method.:]: This 

 consists in the volatilization of the hydrides of these metals 

 which are separated from the hydrogen which forms at the 

 same time by passing the gas through silver nitrate solution. 

 A special form of apparatus was used which consists of a 1 

 liter round-bottom flask with long neck 35 mm wide at the top. 



* Two separate determinations. 



f Zeitschr. anorg. Chem., ix. 149, 1895. 



\ Lunge, Chem. -tech. Methoden, ii, 322. Zeistchr. analyst. Chem., xx, 503. 



