324 PROCEEDINGS OF SECTION B. 
acid reaction, and had a specific gravity of 1-060. It contained 
8°59 per cent. of soluble salts of the following approximate com- 
Position :— 
(9) 
Na,SQ,... oe ae aa 0. O26 
Nal... ae. see ‘= - | BIOS 
Al, (SO,)s ae Bi aes owe wales 
CaSO; ... 7 Re pis sive nd eee 
ZnSO, ... on en AE: wae | DAS 
MgCl ... Ae Ae He at ‘49 
CuCl, .«.. ae bile a of “34 
Bele. 2. ate ae ays ... trace 
Na,AsO, ay ah 2a “le 
In speaking of the wash-water, we are brought face to face with 
one of the most interesting problems, from both a chemical and 
metallurgical point of view, connected with the Russell process. 
This is the so-called going-back of chlorination. This term is 
applied to the marked decrease in the percentage of the silver in 
the ore which is soluble in ordinary solution produced by the pre- 
liminary washing with water, and was originally ascribed by Mr. 
W. 8. Morse, who was one of the first to investigate the matter, 
to the effect of undecomposed blende in the charge reacting on the 
silver chloride (which is soluble in ordinary solution) forming the 
insoluble sulphide. 
Stetefeldt, in speaking of this matter,* says :—‘ ZnS in roasted 
ore is the principal, and in many cases the only cause of chlorina- 
tions going back.” And, again :—7‘‘ The Aspen statistics seem to 
indicate that that portion of the going back of chlorinations, which 
is not corrected by the extra solution, is due to the effect of caustic 
lime, the effect of the latter being to precipitate gelatinous com- 
pounds round the particles of silver.” 
Mr. W.S. Morse in a recent paper, in reviewing this subject 
adheres to his original theory ; but Mr. L. D. Godshall, in criti- 
cising this paper, ascribes this going back to the presence in the 
ore of sulphurous acid, ferrous sulphate, or some other reducing 
agent, which converts the soluble silver chloride into metallic 
silver, almost insoluble in ordinary solutions under the ordinary 
conditions of working. 
It seems to me that there is still another and a very important 
cause for this going-back, which, however, only operates when the 
wash-water is acid, as it was at Rivertree, and frequently is else- 
where. Once a vat has been used for leaching, the material of 
which it is built becomes more or less impregnated with hypo- 
sulphite salts. On adding the wash-water to a fresh charge of ore 
in such a vat, a small quantity of sodium hyposulphite goes into 
* Lixiviation of silver ores with hypo solutions, 1895, p. 65. TIbid, p. 67. 
