SCIENTIFIC SUMMAEY. 
C73 
of forests to continue on the same scale as at present, the price of wood 
would be exorbitant in a very short time. The great consumption of char- 
coal induces landed proprietors to cut their wood every fifteen or sixteen 
years, and even oftener, instead of every eighteen or twenty years, in order 
to get more wood fit for charcoal, and more bark — the price of which has 
doubled. Great Britain has only 2 per cent, of forest land ; Spain only 3 
per cent. ; France has still 16*7 per cent. ; but if things continue on the 
present footing, a few years will reduce it to the condition of these countries. 
How to prevent the Oxidation of Steel aiid Iron . — The most novel process 
for the above purpose is that of M. Chambeyron, by which it is proposed to 
prevent rust in steel and iron by the forced incorporation of these materials 
with the volatile metals having little affinity for oxygen. Tinning, zincking, 
and leading, give only incomplete results, and M. Chambeyron has discovered 
that it is only by incorporating into the iron itself, and to a certain depth, a 
metal or alloy little affected by the action of oxygen, and considered prac- 
tically inoxidisable, that iron and steel can be protected from rust in sea and 
other waters. The method he employs is to introduce zinc alone in a state of 
vapour into the iron and steel, when these are intended for exposure to the 
action of oxygen alone ; and a volatile alloy of zinc, tin, and lead, when the 
metals are to be exposed to other influences. A high temperature being 
necessary to vapourise the metals, the operations are conducted in cementing 
chambers. To each of the cast-iron heads of the upper retorts is adapted a 
tube, the lower extremity of which dips into the retort, the upper end being 
terminated by a funnel, which has underneath a spheroidal reservoir, fur- 
nished above and below with a tap for shutting 'off communication either 
with the retorts or with the interior of the reservoir. The metals to be 
incorporated are poured in a state of fusion into this funnel, whence they fall 
into the retort, the high temperature of which converts them very quickly 
into vapour. In case the pressure produced by the vapour is not strong 
enough to effect the incorporation, a part of the gas of the gasometer is 
caused to flow into the retort, and thus increase the pressure. When the 
metallic vapours have been incorporated in the pores of the iron and steel 
they are condensed by the diminution of the temperature. We are not 
aware whether M. Chambeyron’s process has been yet properly tested, but 
its principle certainly promises well. 
Metallic Tungsten . — It is stated in the Mechanics' Magazine that a 
Swedish metallurgist has discovered a means of reducing tungsten, by which 
he obtains it at once in a state of fusion, and that ingots of the pure metal 
weighing several pounds each are now on exhibition at Stockholm. It is 
alleged, too, that the cost of obtaining tungsten by the new method does not 
exceed a few shillings per pound. If really obtainable thus cheaply, a inetal 
which will bear exposure to so intense a heat without undergoing either 
fusion or oxidation must prove of incalculable value to certain of the arts, 
provided that the difficulties in the way of working it are not insuperable. 
With the exception of gold and platinum, tungsten is the heaviest metal yet 
known. Its specific gravity is about 18, that of gold being 19 '36, and that 
of platinum 21 '53. 
An improved form of Iron . — An improvement in iron (says a New York 
paper), increasing greatly its tensde strength, is claimed by Mr. J. B. 
