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POPULAR SCIENCE REVIEW. 
volumes of sea-water. After one month the plates were taken out, and any 
compounds that had adhered to their surfaces having been carefully removed, 
were then dried and re-weighed and the loss estimated. Calculating the 
action of 100 litres of water upon one square metre of metal, the extent of 
alteration was found to be represented by the following figures ; — 
Metals. Grammes. 
Steel 29-lG 
Iron 27 ’37 
Copper 12 ’96 
Zinc 5 ’66 
Tin 1-45 
Galvanized Iron 1T2 
Lead a trace. 
Vide Chemical Neivs, April 14th. 
The Treatment of Sulphur Gold Oi'es. — Messrs. Crosby and Thomson, of 
California, have pointed out a new method of treating auriferous sulphurs. 
Observing that the difference between the assay value of gold ore and the 
quantity of gold extracted was not accounted for by the gold remaining in 
the tailings, these gentlemen have conducted a long series of experiments 
which have demonstrated that gold, if not volatile, is so nearly so that the 
practical working of it is the same as if it were. It cannot be denied that 
the sulphur carries the gold, and it is observed that these auriferous sulphates 
of iron, by some natural system, are nearer the surface the further north 
they are found. In the new process, the ore, after being crushed into a fine 
powder or sand, and being generally wet, is passed through a drying cylinder 
some ten feet long by tlu-ee feet in diameter ; the latter revolves on a hollow axle 
perforated, through which oxygen can be passed to perfect desulphurisation, 
caused by heating the cylinders to a dull red heat. The cylinders are inclined 
sufficiently to carry the ore through ; at the outlet the desulj)hurized ore falls 
into a receiver and the vapour passes out above it. As it travels upwards, it 
pases through spray which cools it and causes the deposition of the metal. 
Brealdng JRocJcs hy Fire. — This method, which, according to historians, was 
the one employed by •Hannibal in cutting his way through the Alps, has 
lately been employed at the Eammelsberg mines in the Hartz mountains. 
In a portable furnace, about 1 g bushel of coke is allowed to burn for thirteen 
hours, the furnace is then removed and the rock left to cool after being 
sprinkled with water. About noon the face of the rock spontaneously 
detaches itself, and after that a further portion is broken. The effects of the 
fire extend to eight inches, and with 1^ bushels of coke from 1,600 lb. to 
2,400 lb. weight is obtained at half the cost of the gunpowder process. — 
Vide The Artisan, June, 1865. 
N'eio Process for the Manufacture of Zinc. — This, which has been patented 
by Mr. James Webster, of Birmingham, consists in bringing the zinc ore, 
or oxide of zinc, in a finely divided state, into the presence of molten iron 
or any substance which melts at a temperature higher than that of the vola- 
tilising point of zinc. He adapts to a cupola a vessel containing the pulverized- 
zinc ore, which, together with nitrate of soda also pulverized, is carried down 
