Five cwt. of tar, produced 5880 cubic feet of gas, = 101⁄2 cubic feet of gas to 1 lb. of tar.
Two cwt. of tar, produced 2072 cubic feet of gas, = 91⁄2 cubic feet of gas to 1 lb. of tar.
Three cwt. 18 lb. of tar, produced 3717 cubic feet of gas, = 101⁄2 cubic feet of gas to 1 lb. of tar.
Two cwt. 6 lb. of tar, produced 22421⁄2 cubic feet of gas, = 93⁄4 cubic feet of gas to 1 lb. of tar.
From the preceding operations it becomes obvious, that 91⁄2 cubic feet of gas, were obtained in the large way from 1 lb. of tar. But this proportion appears evidently too small, our own operations assign fifteen cubic feet of gas to one pound of tar. Professor Brande, obtained eighteen cubic feet[56] from the same quantity of tar.
[56] Journal of Science and the Arts, 1816, No. II. p. 282.
Gas from Oil.
“Messrs. J. and P. Taylor[57] are the first persons who have resorted to oil as a substance from which gas for illumination could be easily and cheaply prepared; and in the construction of a convenient apparatus for the decomposition of this body, they have fully shewn its numerous advantages over coal, while they have afforded the means of producing the most pure and brilliant flame from the inferior and cheap oils, which could not be used in lamps. The apparatus for the purpose is much smaller, much simpler, and yet equally effectual, with the best coal gas apparatus. The retort is a bent cast iron tube, which is heated red by a small convenient furnace, and into which oil is allowed to drop by a very ingenious apparatus; the oil is immediately volatilized, and the vapour in traversing the tube becomes perfectly decomposed. A mixture of inflammable gases, which contains a great proportion of olifiant gas passes off; it is washed by being passed through a vessel of water (which dissolves a little sebacic acid, and which seldom requires changing), and is then conducted into the gasometer.”
[57] Copied from the Journal of Science and the Arts, Vol. VI. p. 108.
“The facility and cleanliness with which gas is prepared from oil in the above manner, may be conceived from the description of the process. A small furnace is lighted, and a sufficient quantity of the commonest oil is put into a small iron vessel, a cock is turned, and the gas after passing through water in the washing vessel, goes into the gasometer. The operation may be stopped by shutting off the oil, or, to a certain extent, hastened by letting it on more freely; the small quantity of charcoal deposited in the retort is drawn out by a small rake, and the water of the washer is very rarely changed.”