730 



GEOLUGY AjND MIXING INDUSTRY OF LEADVILLE. 



uiouj- and arseuic, which exist ouly iu small qiiautities iu the ores. This accreliou 

 coutf.ius tiu, 5.6 per ceut. ; autimouy, 2.7 per ceut. ; aud arseuic, 5 per ceut. 



The behavior of this accretion with reageuts is noteworthy : treated by weak 

 nitric acid the metallic grains and sulphides, as well as the excess of the oxide of lead, 

 are dissolved and the yellowish compound is left untouched. This residue, treated by 

 strong nitric acid, yields arsenite of lead, which dissolves in the state of arseniate. The 

 residue, which is still yellow, is decomposed by sulphide of ammonium, which dissolves 

 tin. The residue, treated by weak nitric acid, in order to dissolve the sulphide of lead 

 formed, leaves behind a yellow powder, which proves to be autimoniate of> lead. The 

 separations in this instance are so remarkable that the relative proportions of arsenite, 

 antimouiate, and stanuate of lead formiug the yellow compound could iu this way be 

 roughly estimated. 



Analysis XLIII. Peculiar accretion. 



Elementary analysia. 



Katiooal analysis. 



Lead 



Silver , 



Gold 



Arsenic 



Autimonj 



Tiu 



Iron ./. 



Zinc 



Sulphur 



Oxygen 



Peroxide of iron . 



Aluuiin.i 



Silica 



70. 03119 

 0. 29700 

 0. C0075 



5. 00925 

 2 69CS6 

 6.59341 

 0. 02800 



Trace 

 2. 6UU67 



6. 25617 

 3. 43000 

 0. 00000 

 2. 83000 

 0. 00007 



80. 623 



0. 21875 



Metallic grains; 

 Lead 



Silver 



Arsenic. 



Antimony 



Tin 



Sulphide of lead 



Sulphides- 

 Sulphide of iron 



Sulphide of silver 



Sulphide of lead 



Oxide of lead compounds — 



Oxide of lead 



Oxide of zinc 



Arsenious acid 



Autimonic acid 



Stannic acid 



Oxide of gold 



Silicic acid 



23. 72921 

 0. 19800 

 0. OJ50O 

 0. 05500 

 0. 23100 

 0,21913 



0. 0J40i) 

 0.11360 

 18. 9092T 



32. 62459 

 Trace 

 6. 57900 

 3. 50S06 

 6. 81006 

 0. 00075 

 2. S3000 



Discussion. — The rational report may be expressed under the simple form 



Metallic graius 24. 4.^734 



Metallic sulpbiik-s lit. 1-2693 



Oxide of lead coiupouuds 5li. 4 150i) 



Loss 0.00067 



Total loo. OOOOO 



The writer has found that silicic acid, aUimiiia, and jieroxide oi iron were com- 

 bined with oxide of lead in the state of silicate, alumiiiate, and ferrite; as lor gold, it 

 is a well known fact that this metal is oxidized bv oxide of tin and combines with it. 



