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POPULAR SCIENCE REVIEW. 
to heat the oxide to dull redness before allowing it to enter the blast pipe. 
— Vide Mining and Smelting Magazine , February. 
Coating Iron with Aluminium. — Mr. Wm. Clark has invented a peculiar 
process for covering the surface of iron with a layer of the latter metal. 
The surface of the iron is first cleansed ; a mixture is then made of porce- 
lain-clay, feldspar, and white lead, properly ground and incorporated ; 
then about ten parts of this combination are added to about five pounds of 
calcined and powdered alum-clay. This last mixture having been made 
into a thin paste, and poured over the surface of the metal, the latter is 
dried and placed in a reverberatory furnace until it presents a glazed 
appearance. When the iron is removed it will be found to have received 
a tough, adhesive, and elastic coating, which is so closely attached to the 
metal that, when this is bent even at right angles, no symptoms of cracking 
appear. This coating is also unacted on by acids and alkalis. It is 
supposed that during the baking-process the aluminium is separated from 
its oxide and forms a thin metallic stratum, intermediate between the iron 
and the glazed surface. — Ibid . 
New Method for the Extraction of Silver. — This has been adopted by 
Ziervogel, in order to remove the silver from copper regulus. There are 
three stages in the process : — 1st, the roasting of the ground ore. This is 
effected in a reverberatory furnace, and in itself is a double process ; viz., 
the conversion of the sulphides into the sulphates, and the decomposition 
of them, so that, while the sulphate of silver remains unaltered, the other 
sulphates are deoxidized ; 2nd, the lixiviation and precipitation of the 
silver by means of copper ; and, 3rd, the drying and refining of the silver 
itself. It is stated that this method has superseded that of Augustin, which 
was formerly employed at the Mansfeld Copper Works. 
An Improved Form of Davy -lamp has lately been patented by Mr. P. 
Bourne. Its peculiarity consists in a means of extinguishing the flame in 
the act of opening the lamp, and before the wire gauze can be removed. 
There is attached to the lamp, near the neck-holder, an apparatus, com- 
posed of one or more levers mounted on a suitable fulcrum, and which 
apparatus is capable of being depressed on the wick by the act of removing 
the wire-gauze covering. The apparatus is, by the application of a suitable 
spring or springs, kept out of the way of the ignited wick, so long as the 
gauze covering remains on, or when it is being placed on the lamp ; but 
as soon as an attempt is made to elevate the covering, the series of levers 
comes into play, and the wick being pressed on, the flame is consequently 
extinguished. — Vide The Artizan> February. 
Our Iron Exports to France have fallen off sadly of late, whilst the 
exportation of pig iron has remained nearly as it was in 1862. The value 
in money of the iron exported to France in the first ten months of 1863 
was only £174,238; the value of that exported during the corresponding 
period in 1862 being £824,774. It is difficult to account for the dimi- 
nution, but some attribute it to the fact that the prices in France have not 
risen proportionately to the rise established in England and Belgium. 
Novel Electric Fuse for Blasting Purposes. — This, which is a French 
invention, differs from all those previously employed, and appears to be 
highly spoken of. It admits of being rapidly manufactured, whilst the 
