THE ANALYST. 117 TREATMENT OF ORES OF LEAD AND ZINC. ALL metallurgists are familiar with the difficulties which have always been encountered in the attempt to treat these ores profitably, and immense masses of them have either been left altogether unworked or the waste portions have been thrown into heaps, encum- bering the mines with useless deposits. The specific gravity of the different ores are too similar, and their union frequently too intimate, to admit of merely mechanical separation, and apparently up to the present time no efficient chemical means of separa- tion seem to have been found, unless by processes involving so much expense as to make them unprofitable.In reference t o the extraction of the zinc, there is not, of course much difficulty theoretically in separating it by distillation ; but practically, the concen- tration of the lead remaining in the guangue has presented almost insuperable obstacles ; while if it be attempted to separate the lead and reject the zinc, the zinc has a tendency11s THE ANSLYST, to form a hard scoria, not only retaining much lead, but also holding back much of the silver which ought to be taken up by the lead, so that the consequence is a greatly diminished yield of lead, and that which is obtained is less argentiferous.Mr. Maxwell-Lyte, of Paris, has just published some processes which appear likely to remove a considerable amount; of the dffieulty which has been experienced with these ores. It is impossible in the space a t our disposal t o enter into a detailed account of the methods which hc proposes, but we may say that in the main they consist of a combina- tion of the wet and dry methods.Thus, in one of the cases to which he refers the mixed ore is treated in the first instance with dilute hydrochloric acid hot, by which means the zinc and lead are both chloridized, the lcad being more or less dissolved, the zinc entirely so; while on cooling the solution the chloride of lead is deposited, because of its relatively slight solubility in the cold liquid.The clear solution is poured back on t o the residuary guangue from which it was decanted, and again heated and rede- canted, when it carries over a fresh portion of lead. Thus the guangue, deprived of its lead as well as its zinc, may be thrown away. The silver also all passes over with the lead.The deposit of chloride of lead and silver is now reduced to a spongy metallic state by placing in the solution bars or lumps of metallic zinc, while all the zinc remairs in solution, whether that contained in the ore or that which had dissolved in the process of reduction of the lead and silver. This spongy lead may be easily fused in a rerer- batory furnace, and subsequently desilverized. The zinc from the decanted liquors ia precipitated by lime, washed and pressed into bricks, forming a kind of artificial calamine, containing from 60 to 70 per cent. of metallic zinc, and is ready for treatment by distil- lation. I n this way Mr. Naxmell-Lyte considers that he can extract from ores all the lead and silver, while the zinc is also recovered in an available form free from lead, Several alternative processes are also described, but the one of which we have sketched an outline shows his ideas.