124 
POPULAR SCIENCE REVIEW. 
The sulphate procured by this process is dissolved in acid, the platinum 
electrodes of a pile are introduced into it, and the current being properly 
regulated, the metal is deposited in flexible homogeneous plates. The 
copper thus prepared is absolutely pure, and the most precise tests fail to 
discover the slightest trace of any foreign substance. 
Preservation of the Iron Plates of Ships. — Dr. Grace Calvert has contri- 
buted an article to the Chemical News , for Aug. 29, which contains a 
description of a most important discovery. He finds that when iron is 
coated with zinc, or, in other words, galvanized, its capability of resisting 
the corrosive action of both salt and distilled water is thereby intensified. 
Plates of iron three inches square were attached with great care to pieces 
of oak of the same surface, and similar plates of galvanized iron attached 
in the same manner were submerged in both distilled and salt water, and 
allowed to remain there from March, 1862, to May, 1863. When at this 
period the iron plates were carefully removed, washed, dried, and weighed, 
the following results were obtained : — 
Loss by Corrosion, 
in grammes. 
Pieces of wood and iron \ P di ,f lle ? water 
j m salt water 
Pieces of wood and gal- 1 in distilled water 
vanized iron j in salt water 
1-700 
4-320 
0-500 
0-780 
The loss occasioned by the employment of ungalvanized iron does not 
depend on the corrosion alone ; the iron enters into combination with the 
gallic and tannic acids of the oak, and thus the wood decays, or undergoes 
eremacausis. The coating of zinc is not easily removed by friction. 
“ Large bolts (galvanized) were driven into solid blocks of oak by a sledge- 
hammer ; the blocks were then opened, and the bolts were found not to be 
in the slightest degree uncoated.” 
Cadmium Alloys. — Mr. Abel, of Chancery Lane, London, has patented a 
method of forming alloys of this metal with gold, silver, and copper. Those 
with the two latter are said to possess the property of ductibility in a 
high degree, whilst those with gold are capable of being employed in 
jewellery, owing to the beauty of their colour. 
Boring Machines. — The great difficulty which was presented by the old 
forms of borers, viz., that of removing with the augur the whole of the 
rock which it was necessary to bore, has been got rid of by M. Leschot. 
In his apparatus, the perforator is of an annular character, and only cuts 
out as it were a cylinder of rock, leaving a central solid portion, which 
can afterwards be removed by other means. The instrument consists in 
a hollow iron tube, whose outer diameter is proportionate to the required 
size of the hole, and whose calibre corresponds to the size of the central 
portion of the rock. This tool is provided at its end with a perforator 
carrying black diamonds ; it is given a rapid rotatory motion when em- 
ployed in boring, and the powder produced by the cutting of the stone is 
washed away by a stream of water forced along the central hollow portion. 
This machine is at present undergoing trial at the St. Chamond mines. 
Steel Rails. — The rails of steel prepared by Bessemer’s process have 
been submitted to a severe test, and have realized the most sanguine expec- 
