SCIENTIFIC SUMMARY. 
377 
totally different from tlie pick machines, and similar to the action of a 
slotting machine. The cutter-carrier acts direct from the machine. The 
fixing of the machine to its proper locality, and its adjustment to the progress 
of the work, is entirely self-acting. It cuts the shale which is underneath 
the seam, and this preserves the coal entire. It does this at the rate of 80 
square feet per hour, or about 86 yards in length, by 3 feet 3 inches in depth 
of cutting, in 10 hours. One of these machines is nearly ready for operation 
at Cramlington, and another is ordered for Backworth Colliery. — Vide The 
Artizan. 
Novel Application of Magnesium ! — An American paper recommends that 
war-vessels should be built of magnesium, which, while little heavier than 
oak, is as strong and tenacious as steel. The abundance of magnesium is 
the reason of this strange suggestion. It is estimated that the ocean itself 
contains 160,000 cubic miles of magnesium, a quantity which would cover 
the entire surface of the globe, both sea and land, to,a thickness of more 
than eight feet. In obtaining salt from sea-water, the residuum is largely 
magnesium. 
Effect of Heat upon Yellow Diamonds. — Some very curious facts connected 
with the effect of heat on the colour of yellow diamonds were pointed out in 
May last to the French Academy by M. Fremy. This gentleman exhibited 
a diamond weighing about four grammes, which, under its ordinary condition, 
is slightly tinted yellow ; but which, when submitted to a high temperature, 
assumes a rose tint, which it possesses for several days, being only gradually 
restored to its original hue. The diamond, which, at the time of exhibition, 
had the rose-colour, was kept in the cabinet of the Institut until the next 
meeting, when its original yellowish tint was restored. Now, the price of 
an ordinary diamond of the weight we have mentioned would be about 
60,000 francs ; but, with the delicate rose tint, it would be worth three times 
as much. 
The Hagan Process for Desulphurizing and Disintegrating Gold and Silver 
Ores. — An American scientific journal gives the following explanation of this 
useful process. Superheated steam is introduced into fire in such a manner 
that in gaseous form the steam impinges upon the ignited coals or wood 
without mixing with atmospheric air, and thus effects the decomposition of 
water into oxygen and hydrogen gases. The former immediately unites with 
the carbon of the coals, while the liberated hydrogen passes from the fire, 
and burns in the presence of the oxygen in the air. The hydrogen flame and 
the resulting gases being brought into contact with the heated gold and silver 
ores, the sulphur, arsenic, antimony, &c., are dissolved, and are carried off 
with the products of combustion. The powerful effect of the flame of hydrogen 
in dissolving pyritous sulphur, arsenic, antimony, &c., and in attacking oxygen, 
is well known ; but the expense of producing it has hitherto prevented its 
application to the disintegration and desulphurization of gold and silver ores. 
Not until the invention of Dr. Hagan’s cheap and simple method of decom- 
posing water, and thus furnishing hydrogen gas and flame abundantly, has it 
been at all possible to apply it to this purpose. Furnaces are now operating 
by this process in California, which receive charges of sixty tons, and are 
eminently successful. — Vide American Journal of Mining , May 19. 
A j Rotary Eock-boring Drill. — A patent has recently been taken out at 
