TIN AND ANTIMONY. 87 



hot water to free it from the nitrate of baryta which it 

 carries down. 



Both compounds may also be analyzed with great 

 accuracy by means of chlorine gas, as described in the 

 article upon Grey Copper-ore, or Tetrahedrite. 



In analyzing a mixture of light and dark red silver- 

 ore, the arsenic and antimony are separated according 

 to the method described in No. 61. 



60. TIN AND ANTIMONY. 



The weighed compound is dissolved in hydrochloric 

 acid, with gradual addition of nitric acid, and a piece 

 of pure tin placed in the solution, with which it is 

 heated for some time, until the whole of the antimony 

 is precipitated ; the latter is collected upon a weighed 

 filter, washed, dried at 100, and weighed; the amount 

 of tin is inferred from the difference. 



In order to determine both metals directly, the com- 

 pound, as finely divided as possible, is oxidized in a 

 beaker with strong pure nitric acid, the mass evapo- 

 rated to dry ness, gently ignited, and fused, in a silver 

 crucible, with a large excess of hydrate of soda. When 

 cool, the mass is treated with water, rinsed out into a 

 beaker, and the solution mixed with J its volume of 

 strong alcohol. The insoluble antimoniate of soda is 

 thus separated from thestannate, carbonate, and excess 

 of hydrate of soda, which are dissolved by the weak 

 spirit. When the liquid has become perfectly clear, 

 the precipitate is filtered off, and washed, first with a 

 mixture of equal volumes of alcohol and water, and 

 .finally with strong alcohol. 



The alkaline solution is heated to expel the alcohol, 

 diluted with water, acidified'with dilute sulphuric acid, 

 and the tin precipitated by sulphuretted hydrogen 



