SHAFT ACCRETIONS. 



727 



mide of lead, a small quantity of iodide of lead. They appeared, moreover, to Lave 

 the satue composition as the chloro-broiuo-iodide of lead which was fonud by the 

 writer iu the lead dust; in which case they would contain more chlorine than bromine 

 and more bromine than iodine ; but being crystallized it is very possible that they 

 have the composition assigned to them by Dr. M. W. lies and the formula Pb Br 

 Cl. These crystals form quite an accidental accretion, and are found only iu very 

 small quantity. 



The normal accretion, the one found iu every smelter and in every furnace, is a 

 light crystalline fibrous and porous mass with a luster like galena and full of cavities, 

 spotted with a whitish-yellow and reddish crust. The fibrous portion is formed of 

 alternate layers of galena like and of yellowish white crystals. Xo metallic grains 

 can be seen in the mass of the accretion, even when broken into very small bits ; but, 

 while some parts are quite brittle, others have a toughness which is due to the pres- 

 ence of metallic lead. A similar accretion, collected at Messrs. Billing & Eilers's 

 smelter, was separated by the sieve into powder, 81.25 ; lead grains, 18.75. 



The whole accretion, powder and grains, was analyzed iu the above proportion 

 and found to contain, among other substances, an enormous quantity of metallic lead; 

 more than twice as much as the quantity represented by the lead grains. This lead 

 is evidently condensed vapor of this metal or sublimated lead, so intimately mixed 

 with the sulphides that it passes through the sieve. 



Another point of interest is the large percentage of sulphide of zinc found, 

 which forms the yellowish white crust and layers visible iu the accretion already men- 

 tioned. 



The following is the analysis of a typical shaft accretion collected at Messrs. 

 Billing & Eilers's smelter. 



ANALYSIS XLII. SHAFT ACCRETION. 

 1'urtion soluble in adds 



Elementary analysis. 



Rational analysis. 



Per cent. 



Sulphur 82912730 



Lead 47.4912340 



Bismuth Trace 



Silver 0.0754498 



Gold Trace ouly 



Copper Trace 



Z.nc 69774000 



Cadmium Marked trace 



Iron 6.7536000 



Arsenic 0.0392089 



Autimony . Trace 



Sulphuric acid 0.9653590 



Phosphoric acid 2.1663252 



Carbonic acid '. Trace 



Lime 4.2616000 



Magnesia 3.20J1540 



Oxide of manganese 2.8871860 



Alumina.. 0.0720000' 



Sulphide of lead 



Sulphide of bismuth 



Sulphide of silver 



Sulphide of gold 



Sulphide of copper 



Sulphide of zinc _ 



Sulphide of cadmium 



1'rotosulphide of iron 



Sulphide of arsenic 



Sulphide of antimony 



Mi'tallic lead 



Sulphate of lime 



Phosphate of lime 



Carbonate of lime 



Caustic lime 



Caustic magnesia 



Oxide of manganese 



Alumina 



Per cent. 



7.20408,0 



Trace 



.'. 0. CS6G208 



Tia<6 



Trace 



10.4124000 



Marked trace 



10.6U9000 



0.0644009 



Trace 



41.2469180 



1.0411103 



4.C937046 



Trace 



1.0584693 



3.2021540 



2.S871860 



07:'0(iOO 



