SHAFT AGCiiETIONS. 727 



iiii<le of lead, a small quautity of iodide of lead. They api)eared, moreover, to bave 

 the same compositiou as the cLloro-brorao- iodide of lead which was fouud by the 

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

 aud more bromiue thau iodiue; but beiug crystallized it is very possible that they 

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

 CI. These crj'stals form quite au accidental accretion, and are found only iu very 

 small quautity. 



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

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

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

 alternate layers of galena-like and of yellowish-white crystals. No metallic grains 

 cau be seen iu 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 se])arated by the sieve into powder, 81.2.5 ; lead grains, 18.75. 



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

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

 more than twice as much as the quautity 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 aud layers visible iu the accretiou already men- 

 tioned. 



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

 Billing & Eilers's smelter. 



AxAXVsis XLII. Shaft accretion. 



Portion soluble in acids 



Elementary analysis. 



Kational analysis. 



Per cent. 



Sulphur 8.2912730 



Lea.l 47.4912340 



Btsmulh Truce 



Silver 0.0754498 



Gold Trace ouly 



Copper Trace 



Per cent. 



Siilphiaeoflead 7. 20498.,0 



Sulphide of bismuth Trace 



Sulphide of silver 0. P(>6C2G8 



Sulphide of gold Tiaie 



Sulphide of copper Trace 



Sulphide of zinc 10.4124000 



Zinc 6.9774000 i Sulphide of cadmium Marked trace 



Cadmium. Marked trace I Protosulphide of iron 10.0129000 



Irou 6.7536000 1 Sulphide of arsenic O.C644009 



Arsenic 0. 0392C89 i Sulphide of antimony Trace 



Antimony Trace j Metallic lead 41.2469180 



Sulphuric acid 0.9653590 Sulphate of lime 1.6411103 



Phosphoric acid 2.1663253 Phosphate of lime 4. C937048 



Carbonic acid Trace i Carbonate of lime Trace 



Lime 4.2616000- Caustic lime 1.0564693 



Magnesia 3.2021540 Caustic magnesia ,7.2021540 



Oxide of manganese 2.8871860 Oxide of manganese 2.f8718eo 



Alumina 0.0720000 Alumina 0,0720000 



