Page:Transactions of the Provincial Medical and Surgical Association, volume 2.djvu/128

 readily distinguished from the latter by its black colour. Besides the more sensible effects on the air of mines by the explosion of gunpowder, it must deteriorate it, in a still greater degree, by introducing so large a quantity of irrespirable gases into it. The gases generated by the explosion of gunpowder are carbonic acid gas, azote, sulphurous acid gas, and, perhaps, sulphureted hydrogen. These are all injurious to respiration, inasmuch as they are all either hurtful stimuli to the air passages, or are destitute of oxygen, or possess both these qualities combined.

Their amount is very considerable, estimated relatively with the spaces in which they are generated. It has been ascertained by experiment, that the gases occupy 244 times the volume of the powder from which they are extricated, supposing them to be, when evolved, of the same density as the atmospheric air. Allowing for the expansive effect of the heat generated at the time of explosion, it has been calculated that they will occupy 1000 times the space occupied by the original powder. Now, admitting a pint of gunpowder to weigh somewhat more than 14 oz. and allowing 60 pints to the cubic foot, we have thus 1000 cubic feet of gas for 50 lbs. of gunpowder, or 20 cubic feet for 1 lb. taking into account the effect of rarefaction. This will give 176,200 cubic feet of irrespirable gases generated per month, in the six mines above mentioned.

The air of mines is still further deteriorated by the consumption of oxygen, and the generation of