EXPERIMENTS WITH CARBONITE.

BY M. WALTON BROWN AND WILLIAM FOGGIN.

As the experiments with carbonite at Cymmer Collieries showed that when fired in a cannon and unstemmed it might ignite explosive mixtures of natural gas with coal-dust, the following further experiments were made at the North Biddick Collieries in order to determine this question more exactly.

I. DESCRIPTION OF THE APPARATUS. (PLATE XIII.)

The apparatus used consisted of a gas chamber and a cannon.

The gas chamber, a (with a capacity of 126 cubic feet), was made from a boiler! tube 17 feet 10 inches long, and 3 feet in internal diameter, and one of whose ends, b, was covered with a flat plate, with an opening 10 inches in diameter. This chamber was simply laid upon the soil.

The cannon, c, was made of forged iron, 11 inches in diameter and 4 feet 7 inches long, fitted with holes 14 inches diameter, at one end 18 inches long, and at the other end 14 inches long. This cannon was firmly secured to a small tram, d, by which it could be withdrawn from the partially closed end of the boiler, re-charged, returned into position, and fired into the boiler, whose axis and that of the cannon were coincident.

The gas chamber was fitted with two openings, e and f, on the top, each 8 inches diameter, and with a sight hole, g, 10 inches by 8 inches, which was covered with a strong iron framed glass window.

The gas chamber was closed at the open end, h, with a sheet of brown paper, firmly secured to the end of the boiler by an india-rubber ring. The other and partially closed end was covered by the cannon, and made more perfectly tight by an india-rubber wheeze.

A fan blade, i, was fitted in the middle of the length of the gas chamber, and could be rapidly vibrated by means of an external lever and a long cord, k.

Ordinary lighting gas was supplied from Messrs. Newall & Sons' gas works, near Washington station, and was measured into the chamber through a 50-light meter, and discharged into the boiler about 12 inches from the firing end.

Each charge was fired with one No. 6 Nobel detonator, by means of one of their electro-magnetic exploders.

II.-CARRYING OUT OF THE EXPERIMENTS.

The experiments were made under the same conditions as were in force at Cymmer Colliery as far as practicable. The shots were fired without stemming into the explosive mixtures, containing from 10 to 15 per cent. of gas mixed with air.