314 Browning and Scott — Detection of Germanium 



cm^ of water. The test tube was then immersed in a beaker 

 containing snow, ice, or cold water. As a substitute for the 

 passing of chlorine gas, a little potassium permanganate, man- 

 ganese dioxide, or potassium chlorate was placed in the flask 

 with about 10 to 15 cm^ of strong hydrochloric acid and the 

 germaniferous zinc oxide. The liquid in the flask was slowlj 

 brought to the boiling point, and about one-half distilled. Bj 

 this method 1 grm., in another case 0*5 grm., of the oxide 

 gave a distillate from which a heavy white precipitate was ob- 

 tained with hydrogen sulphide 0"1 grm. gave a decided precipi- 

 tate, and '125 grm. a noticeable trace. From these results it 

 would appear that less than O'OOOl grm. of germanium can be 

 detected by this procedure. 



This method was applied successfully to a small sample of 

 the mineral argyrodite previously decomposed by nitric acid, 

 the product having been evaporated to dryness to remove ex- 

 cess of acid. The amount of germanium sulphide obtained from 

 the weighed sample of mineral taken indicated the presence of 

 about 8 per cent of germanium, which is very close to the per- 

 centage given for argyrodite. 5 grm. of a leady residue from 

 the purification of zinc, which had given spectroscopic evidence 

 of germanium, gave a noticeable test for that element by this 

 method. 



To further conflrm these results a solution of germanium 

 sulphid in ammonium hydroxide was prepared, containing 0*001 

 grm. in a cubic centimeter, reckoned on germanium. Portions 

 of this solution were used to determine the delicacy of the test, 

 and it was found that 0*0001 grm. conld always be easily de- 

 tected, even in the presence of 0*2 grm. of pure ZnO, and 

 0-00006 grm. gave a satisfactory test when present with 0*025 

 grm. of ZnO. 



A series of tests for germanium was prepared by one of us 

 and given to the other, without the experimenter's knowledge 

 of the substance present; the results are given below :- 



(1) 0*2 grm. SnCl^ + 0*0005 grm. Ge Reported Ge present. 



Decided white ppt. 



(2) 0-2 grm.SnC]^ Reported no Ge. Very 



faint cloudiness. 



(3) 0-2 grm. As,0^ -f 0*0005 grm. Ge Reported Ge present. 



Same as (]) 



(4) 0*2 grm. As^O^ Reported no Ge. Very 



faint cloudiness. 



(5) 0*2 grm. ZnO + 0*001 grm. Ge Reported Ge present. 



Decided white ppt. 



(6) 0*2 grm. ZnO Reported no Ge. Not 



even cloud3\ 



(7) 0-001 Ge ___ _. Reported Ge present. 



Decided test. 



