COMPOSITION OF LEADVILLE OEBS. 619 



Discussion. In this ore pyromovphite is replaced by anglesite, the sulphuric acid 

 of which plays an important part in smelting. Some of the constituents of this ore 

 arseniates, sulphates, and antimoniates will be found in an almost unaltered condi- 

 tion in some of the furnace products (accretions). The presence of zinc gives a special 

 interest to this analysis, for the reason that this metal is found in every furnace prod- 

 uct lead fumes, accretions, bullion, and slags. But, although the two preceding 

 analyses are typical of the carbonate ores and contain their most important elements, 

 they do not show the metals molybdenum, titanium, bismuth, nickel, cadmium, copper, 

 and tin, which have also been found in the furnace products, and appear to be pretty 

 widely distributed in the camp, though generally in very small quantities. It is, how- 

 ever, evident that certain substances are entirely wanting in some ores. For instance, 

 a special examination of the Little Chief Smelter slag failed to detect more than traces 

 of titanic acid, showing that this substance does not exist in the Little Chief ore, 

 although it is to be found in most Leadville slags. 



Chloride ores In Leadville the chlorides of silver have long been known as 

 cerargyrite and embolite, of which they have the characteristic appearance. The 

 writer made a special qualitative examination of the embolite found in the Eobert E. 

 Lee mine (old workings). This embolite is disseminated in the peculiar antimonifer- 

 ous ocher already spoken of. One specimen gave chlorine and bromine, with a little 

 iodine; another gave less iodine than the preceding, but more bromine. Dr. W. F. 

 Hillebraud has made the following analyses of the chief chlorides of Leadville: 



ANALYSIS III. Robert E. Lee (chloride ore). 



Chloride of silver 21. 580 



Bromide of silver 77.986 



Iodide of silver... 0.425 



100.000 

 ANALYSIS IV. Amie (chloride of rilver contained in hard carbonate). 



Chloride of silver 15. 755 



Bromide of silver 84.091 



Iodide of silver 0.154 



100. 000 



The formula of this chloride is 4AgBr + AgCl(I), a very small quantity of iodine 

 replacing chlorine. 



ANALYSIS V. Big Pittsburgh ore. 



Chloride of silver 99.960 



Bromine of silver None 



Iodide of silver... 0.035 



100. 000 



At the Chrysolite mine a magnificent block of very pure cerargyrite was found, 

 weighing several hundred pounds. . 



In order to determine the relative proportions of chlorine, bromine, and iodine 

 throughout the district, a mixture was made of lead fumes collected in the dust chain- 



