DRAWBACKS TO THE USE OF ACETYLENE.

DRAWBACKS TO THE USE OF ACETYLENE.

PROPESSOR J. VERTRESS, in writing on the subject of acetylene, adverts to some of the drawbacks that accompany its use. He points out that one source of the trouble is the carbide of calcium, from which acetylene is produced. This carbide of calcium is a very hard, black crystaline, which, though not decomposed by heat, is easily decomposed by water into acetylene and lime. Its density is 2.2. It is insoluble in both petroleum and benzine, and concentrated acids have no action on it. It is never pure, as it always containsatleasttwenty per cent.of impurities Theoretically,sixty-four parts by weight of carbide should give twenty-six parts of acetylene—that is to say, 1,000 grammes of carbide should produce 406.25 grammes of acetylene, and as its density is 0.1, one litre weighs 1.16 grammes; wherefore, the 1,000 grammes of carbide ought to yield 350 litres of acetylene. The guaranteed yield, however, is never more than 300 litres—as a rule, a yield of only 280 to 290 litres can be depended upon. In this connection, it must be remembered that during the weighing the calcium absorbs a certain amount of moisture from the atmosphere, which, of course, causes a loss of acetylene. But the small resultant errors, when calculated on 1,000 grammes of material, are multiplied in proportion. It must also be remembered that only small quantities can be worked with, inasmuch as only 1,000 grammes of material give off thirty litres of gas, and it is by no means easy to arrange graduated gas-holders to store such large quantities, while also the carbide, being so far from homogeneous, several samples must be tested and examined before a mean value can be arrived at. On the other hand, if only ten grammes are taken, the error resulting from the disengagement of acetylene in the air will be multiplied one hundred times, if the results are calculated, as they should be, on 1 000 grammes. Professor Vertress has examined the manner In which the carbide behaves in the presence of acids. He found that concentrated sulphuric acid had no action on this body; but that, no matter how little water the acid might contain, bubbles of gas were formed until the whole of the water was consumed. Owing to this property of the carbide not being attacked by concentrated sulphuric acid, it is possible to estimate its acetyleneproducing power.

The acetylene itself is impure. It is a colorless gas, with a penetrating garlicky smell. It is easily soluble in water, and can be liquefied at 0° uuder a pressure of forty-eight atmospheres. In this state it is very explosive. The risk of explosion is all the greater because the acetylene, owing to the sulphur, phosporus, and nitrogen contained in the carbide, is contaminated with sulphurated hydrogen, phosporeted hydrogen, and ammonia, rendering its purification as necessary as that of coal gas—and to the same extent, lest its use in closed places should cause serious accidents.