1872.] Metallurgy. 519 
the pit. An ingenious application of such flames to the construction of a new 
safety-lamp has been made by Dr. A. R. Irvine, of Glasgow. When a mixture 
of an inflammable gas and air, in such proportions as to be explosive, is ignited 
on the surface of wire-gauze, and a suitable tube or chimney is placed over 
the flame close to the gauze, a musical sound is distinétly heard, varying in 
pitch with the magnitude of the flaine and proportions of the chimney, 
Applying this principle, Dr. Irvine has constructed an improved safety-lamp. 
While the atmosphere is not vitiated by fire-damp, the lamp burns quietly ; 
but when the quantity of inflammable gas rises to explosive proportions the 
flame emits a musical sound, and thus the danger appeals to the ear, just as 
in Davy’s ordinary lamp the combustion of the explosive mixture within the 
gauze cage appeals to the eye. Several forms of the singing-lamp have been 
devised. In one form, adapted to the use of the viewer, the air gains ad- 
mission near the top of the lamp, while in another form, adapted to the 
purposes of the working miner, a brilliant light is obtained by the use of 
paraffin oil. 
From an official report recently issued by a special committee appointed by 
the War-Office to enquire into the subject of the transport and storage of Litho- 
fracteur, it appears that the committee, whilst fully admitting the safety of the 
explosive under ordinary conditions, find that, on exposure to a high tempera- 
ture, part of the nitroglycerine separates from the solid substance by which it 
was absorbed, and exudes from the cartridge. ‘lhe explusion of a single drop 
of the pure nitroglycerine might determine the explosion of the entire charge. 
It appears, then, that lithofracteur cannot be said to be a perfeétly safe 
mining explosive. 
It is said that no fewer than twenty-two distiné@ forms of machine for rock- 
boring have been constructed by Messrs. McKean and Co. The ‘*‘ McKean 
Rock Drill ’—the final result of their labours in modifying the Haupt Drill— 
has lately been in successful operation on hard Scotch granite, in which it has 
been drilling holes 2 inches in diameter, at the rate of about 64 inches per 
minute. For use in «he mine, the drill is mounted on a vertical column fixed 
rigidly by a telescopic and screw adjustment. The boring-tool is securely 
fixed to a solid piston moved by steam or compressed air, and kept working in 
suspension, the valve-ports being opened and closed so as to leave a cushion 
at each end of the piston in its reciprocating movement. During the back 
stroke of the piston, a rotatory motion 1s imparted to the boring-tool. 
That coal-cutting machinery has not been more extensively introduced into 
our collieries seems to be due, in great measure, to the enormous cost of laying 
down pipes from the surface to convey the air into the pit, and thence to the 
part of the workings where the machine happens to be in use. This difficulty 
may be to a great extent overcome by a recent invention patented by Mr. E. 
T. Simpson and Mr. F. Hurd. These gentlemen propose to use a portable 
air-compresser, which may be worked in any part of the mine by manual or 
animal power. 
A correspondent of the ‘* Mining Journal” offers for public competition a 
prize of ‘£20 for an essay containing the best description of the principal 
machines and tools used in general mining and quarrying operations, with the 
results of the writer’s experience in their use. 
At the recent Cornwall Polytechnic Exhibition, some experiments were 
made with the Burleigh rock-drill, and with a model illustrating Scott’s plan 
for ventilating mines by inje@ing steam into one of the shafts. Among the 
other exhibits were a model of Willoughby’s Spring Stamps, one of Borlase’s 
patent ore-dressing machines, and an improved pulveriser by Mr. Sara, of 
Redruth. 
METALLURGY. 
From an analysis recently published in the ‘“‘ Chemical News,” it appears 
that a pure wrought-iron has lately been made on a large scale at the Bowling 
Iron Works, at Bradford, by the Henderson process. The wrought-iron con- 
tained 99°5 per cent of iron (by direct determination), with 0-272 per cent of 
