362 Miscellanies. 
cooling. It may also be obtained by solution in hot spirits of tur- 
pentine and subsequent cooling. This process will give, from mut- 
ton suet, more than a third of its weight of stearine, fusible at 60°. 
This is regarded as eminently adapted to bougies, superior to sperma- 
ceti and margaric acid, the former melting at 44° and the latter be- 
low 60°, while stearine fuses at 62°.—Bull. D’ Encouragement, 
Juin, 1834. 
13. J.G. On the cementation of iron by means cf carburetted hydro- 
gen; by M. Durresnoy, Engineer in chief of the mines of France.— 
M. Macryvosuy, one of the best informed manufacturers of England, 
to whom the chemical machinery in the vicinity of Glasgow is in- 
debted for numerous improvements, formed the idea of fabricating 
steel by exposing iron to a current of carburetted hydrogen. After 
various trials, the apparatus which he found the most convenient, 
consisted of a cast iron tube, lined internally with the refractory clay, 
used in the high furnaces of the Clyde. ‘To prevent the shrinking 
which clay commonly undergoes, it is mixed with about one third of 
the same clay, baked, and reduced to fine powder. ‘The tubes em- 
ployed by M. Macintosh vary in length from four to six feet, and 
their interior width from ten to eleven inches. ‘The coating of clay 
is two inches thick: it should be thoroughly beaten, and free from 
fissures. To accomplish this, a cylinder of wood is introduced, whose 
diameter is equal to that of the interior of the apparatus; the clay is 
put on in thin successive layers in the manner practised in the fabri- 
cation of glass-house pots. ‘The tube has adjutages at each extrem- 
ity. One of these serves for the admission of carburetted hydrogen, 
and the other for the emission of the gas. These openings may 
each be accurately closed so as to cause the gas to remain in the 
tube as long as convenient. 
The tube is placed in a furnace so that it may be surrounded on 
all sides by coal. 
Each tube is charged with 100 to 150 pounds of iron, the bars 
being placed lengthwise, and detached by small cross bars, in order 
that the gas may come into contact with the entire surface. After 
the fire is kindled, and the tube is sufficiently hot, a current of car- 
buretted hydrogen is introduced, produced by the distillation of coal. 
But in order that the gas and iron may acquire the temperature re- 
quisite to the cementation, the hydrogen is renewed every half 
hour. During this time the gas is deprived in great part of its car- 
