C. W. Eliot and F. H. aac Impuritiesin Zinc. 145 
“Tn addition to t hat no precipitation is produced by, —— 
salts in the dilute rr nitric acid a v4 ‘the residues from the Php zines, 
would adduce prea exper riments to show that any compound of sulphur =a a 
metal, which might be pre “yp in _ Pare a in all probability, be decomposed 
is presence of an omens of zin e aci 
“ Wackenroder,* in the memoir already ce rye aoe states that the black resi- 
due from zine is sulphi id of lead,—a at first sight sufficiently plenatilas 
but really inconsistent with the — a case. Then precipitated sulphid of 
lead is mixed w — —— excess of granulated a (Silesian, Vieille Montagne, or 
m p or 
are woes a If, after all the aa has been completely dissolved, the insoluble resi- 
due is fused before the eee act et of soda free from sulphuric acid, 
the mass thus obtained will n n si 
“If powdered galena be sSouieed for gene tare sulphid of lead, the same 
ffects i ough mu 
fore, suffers complete ecom posi tion in pre of a ess of zinc and free acid, 
and it is of ae — rman diss “this eek ero: er te found in the 
insoluble res 
an is§ say, that ‘the form 
can only be attributed to the partial dca of the sgivstie acid by the nas- 
rogen.’ Su elain,| dou i 
To obtain a satisfactory solution of be problem, it is necessary to use an acid which 
does sin se fp ealpioor in any form. Sulphuric acid will not answer the purposes 
we hav ee riment ; oe: though it is undoubtedly possible to pre- 
pare suiphurie aeid renee sulphurous acid, Fg the doubt wor ill remai 
cerning the reduction of the 5 salphufic acid by the h gat Rect reduction not impos- 
y concentration. In testing 
cate 
which gives - on itate with rie sai but it is very difficult to _— 
this acid from common salt and sulphuric acid, so that, while containing no chl 
it shall be absolutely free from oe ous acid, or some lower compounds ‘of a 
rm., 1834, 
der Pha * 
: We have observed that ‘the *sulphids of tin and copper are also decomposed er 
mixed with an excess of zine and dilute ae. The we of copper was 
tions Pon, co ee 
ions of sulphur fire his | blow < Siihongat € this mig 
in the tinfoil from which ig 8 = prepared, yet it wal pine thatthe de 
position a len the sulphid of tin is effected wi depukgtes ter difficult y than thst the 
— Coane: Sra 543, in Dingler’s Polyt. Jour. 1841, Ixxali, 425. 
i Ann. de Ch. et Fags 1843, [3,] vii, 189 
Am. Jour. Scl—Srconp SERIEs, Vo. XXXI, No. 91. —Jas., 1961. 
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