IN CHEMISTRY. 1 3 l 



45. What is the test for Ag ? Cu ? 



Ag can be easily detected when in solution by the pre- 

 cipitation of the white curdy chloride, insoluble in H 2 O 

 and HNO 3 , and soluble in H 3 N : the metal can be 

 obtained in malleable globules before the blowpipe, and 

 is reduced from its solutions by Fe, Cu, P, and Hg. Ag 

 is estimated quantitatively either as the chloride or as 

 the metal. 



Copper may be tested (i) by the black insoluble sul- 

 phide ; (2) by the blue hydrate turning black on heating; 

 (3) by the deep blue coloration with ammonia ; (4) by 

 the deposition of red metallic copper upon a bright sur- 

 face of iron placed in the solution. 



46. What weight of crystallized "tin salts" (SnCl 2 , 

 2H 2 O) can be prepared from one ton of metallic tin? 



Sn : SnCl a , 2H a O : : 2000 Ibs. : x. 



118 : 225 : : 2000 Ibs. : x. 



118 x = 450000 Ibs. 



* = 3813-56 Ibs. (SnCl a ,2H a O). 



47. ioo parts by weight of silver yield 132.8+ parts of 

 silver chloride. Given the combining weight of chlorine, 

 required that of silver. 



x : 35.5 : : ioo : 32.8 + . 

 328 x = 3550. 

 x - 108 + . 



48. What is the composition of slacked lime 1 



(See Chemistry, page 137.) 



CaO,H 2 O. 



49. How is ferrous sulphate obtained ? How many tons 

 of crystals can be obtained by the slow oxidation 0/230 tons 

 of iron pyrites containing 37.5 per cent, of sulphur ? 



(See Chemistry, page 155, and Key, page 60 ; Question 33.) 



