ORES AND VEIN MATERIALS. 601 



REMARKS ON TABLE IX. 



The figures in the upper series represent the relative proportions of 01, Br, and 

 I ; those in the second series, the percentages of the corresponding silver salts. 



The ore specimens, having first been treated with nitric acid to extract any solu- 

 ble chlorine salts, were then subjected to the reducing action of zinc and sulphuric 

 acid, whereby the silver salts were entirely reduced. To the filtered solution, contain- 

 ing all the chlorine, bromine, and iodine, potassium nitrite was added, the liberated 

 iodine collected in carbon disulphide, separated wiWi the latter by filtration, and esti- 

 mated by titration with dilute sodium hyposulphite solution. The chlorine and bro- 

 mine were then thrown down by silver nitrate, the precipitate was washed thoroughly 

 by decantation, brought entirely into a tared vessel, fused, and weighed. As suffi- 

 cient material had been taken to insure several grams weight of mixed chloride and 

 bromide, the estimation of the halogens by entire conversion into silver chloride in a 

 current of chlorine gas was repeated on different portions with very closely agreeing 

 results, of which the above are the mean. In Analysis III a qualitative test failed to 

 indicate the presence of a trace of bromine, and the fused silver chloride, when heated 

 in chlorine gas, showed no change whatever in weight. The silver in the ore, reduced 

 by the action of zinc and sulphuric acid, was not estimated. The figures in the second 

 horizontal series above are therefore obtained by calculation from the chlorine, bromine, 

 and iodine found. In Analysis I the proportion of AgChAgBr is 4:11, while in 

 Analysis II it is 1 : 4. 



