The Optical Magic Lantern Journal (June 1896)

94 The Optical Magic Lantern Journal and Photographic Enlarger. it we only put in a charge of one pound (carefully weighed), and after connecting (via E) a Bray’s burner of 0000 capacity, found that the light lasted exactly three hours and five minutes. For lantern work two burners, placed about half an inch apart, are preferable to one only, and this would give, atthe rate of one pound of calcium carbide, and two 0000 burners one hour and a half, or with the basket charged with two pounds, three hours. We find the same fault with this apparatus that we did with the first model of another make of generator that was sent to us, viz., that no means are provided for keeping the condensed moisture from the gas out of the supply pipe. This, as we suggested in our former article, can be easily overcome, and doubtless the Acetylene Gas Company will see the necessity for coping with this drawback. At (c) it will be observed that the tubing takes a turn or bend inside of the gasometer; this is a simple, although very important, addition tc a gasometer of this character. When burning acetylene gas, if the pressure be taken off to a great extent, not only does the gas flame become lowered, but as soon as it becomes lowered it at once begins to give off a dense smoke, which will in a few minutes descend in a perfect rain,” which will settleon everything ina room, much to the discomfort of those who have to attend to the dusting of same. But by means of this little trap or bend (c) all this annoyance is prevented, for if the supply of gas has become practically exhausted, and the gas holder is descending for the last time, just before the pressure is diminished the lower end of this bend dips into the water, at once shutting off this outlet to the gas. The measurements of this generator are 13 by 17 inches. <0 Investigation Concerning Acetylene Gas. In order to put before the public a report on this subject, The Progressive Age of New York have, at great cost, obtained the services of Hidwin J. Houston, Ph.D.A.E., Kenelly, Sc.D., A.LE.E., and Dr. L, P. Kinnicutt, D.Sc., as commissioners to investigate this subject. Although this report is protected by copyright in this as well as other countries, we are indebted to the proprietors of The Progressive Age for permission to publish an extract. The report goes on to state that the first announcement respecting calcium carbide was made by Sir Humphrey Davy, that carbon and potassium when heated to a temperature sufficiently high to vaporise the potassium, formed a compound, which after cooling would elfervesce with water. Berzelius announced in 1836 that the black substance formed in small quantities as a byeproduct in producing potassium from potassic carbonate and carbon was carbide of potassium. Wobhler made carbide of calcium in 1862 by fusing an alloy of zinc and calcium with carbon. He ascertained that it decomposed in contact with water forming calcic hydrate and acetylene. Berthelot in 1866 described sodium carbide or acetylene sodium. He discovered that the high temperature of the electric arc within an atmosphere of hydrogen would unite with carbon of the charcoal terminals and form acetylene gas. Carbide has generally been styled ‘“‘a dark gray substance.’”’ A good quality gives five cubic feet of gas to the pound, and has a reddish tinge. Carbide of inferior quality may be grayish or intensely black in colour. The synthetical possibilities include acetylene, marsh gas, alcohol, oxalic acid, acetic acid, cyanhydric acid, benzene, ethylene, etc. Acetylene as a means of procuring power is dwelt on, and the following comparisons made with respect to coal :— (1) Coal.—The 600,000 horse-power hours will need, at 1,543 lbs. per horse-power hour, 413 tons of coal, occupying, when well stowed, a space of 14,800 to 15,200 cubic feet. (2) Liquid acetylene.—According to Ihering and Slaby’s figures, 04 lb. nearly is required per horse-power with large engines, or 106 tons for 600,000 horse-power hours. A_ specific gravity of -451 at 0 deg. C. corresponds to -364 at 35°8 deg. C. (about the temperature of the ship’s hold); and therefore 106 tons would require vessels of 9,500 to 10,600 cubic feet capacity, and these to be absolutely safe at a pressure of upwards of 50 atmospheres. (38) Calcium carbide.—The corresponding amount of 90 per cent. carbide would be 295 tons, which, at a specific gravity of 2:22, would occupy a space of 4,625 cubic feet, or, allowing for the tins in which the blocks are stored, about 5,300 cubic feet. Therefore, to supply power for 25 days to a 1,000 horse-power engine requires :—Good coal 413 tons, having a volume of 14,800 cubic feet ; compressed acetylene 106 tons, having a volume of 9,890 cubic feet; or calcium carbide 295 tons, having a volume of 4,770 cubic feet. Another point in favour of the use of calcium carbide as motive power is that coal needs a