538 GAS, AIR 



The generator is a kind of box, of sheet iron, in bulk not exceeding two cubic yards, 

 standing upon a shallower box, holding a liquid hydrocarbon. A small dome on tho 

 upper surface covers an ingenious air- or force-pump, moved by clockwork, and capable 

 of easy regulation. The liberation of a weight starts tho operation, and a steady 

 current of air is driven over tho surface of the liquid in tho receiver, which is kept at 

 a constant level. An absorbent substance is employed to increase tho evaporative 

 surface, and to oppose a slight obstacle to the passage of the current, since it is found 

 that, within certain limits, the slowest stream of air takes up tho largest amount of 

 combustible vapour. The hydrocarbon employed is a petroleum or shale-oil of specific 

 gravity '660, somewhat similar, wo believe, to the cheap spirit burned in common 

 sponge lamps. Seventy cubic feet of air, after complete saturation with the vapour, 

 become a hundred cubic feet of 'gas,' of a density of 1*2, air itself being unity. The 

 Kromschroder gas is thus about double the density of coal-gas, and contnint; nearly 

 one-third its bulk of hydrocarbon-vapour. As to illuminating power, the trial l>y 

 Bunseujs photometer proved satisfactory. Burning at the rate of 3 cubic feet per 

 hour, Sugg's improved argand being employed, a light equal to 18'1 candles was in- 

 dicated, which, reduced to tho standard of 5 feet per hour, is equal to about 26 candles, 

 or nearly double the value of gas as usually burned. 



Granting an equality in lighting power, there are three points in which any proposed 

 substitute for coal-gas must satisfy consumers before it can come into use. First, its 

 cost must not be greater ; secondly, it must bear storage ; thirdly, it must ' travel.' 

 With regard to tho first condition, Mr. Kromschroder makes no definite promises, but 

 is confident that his gas can be generated more cheaply than coal-gas. Certainly the 

 process is much less troublesome, and as the machine is self-acting, there can bo but 

 little expense for wages. One gallon of petroleum, worth about eighteenponce, will 

 make about 700 cubic feet of gas, and this is alleged to burn as long as 1,200 feet of 

 ordinary gas, giving a better light. As to storage and travelling power, Mr. Hastings, 

 engineer at the Marlow Gasworks, having had full opportunity for three months of 

 testing the gas in every possible way, and having, to begin with, a prejudice against 

 it, reports favourably. In fact, he says that storage for a week or ten days improves 

 tho gas, his theory being that a chemical union takes place between its constituents. 

 We could not, however, learn that the results of chemical examination confirmed this 

 supposition. Mr. Hastings, we understood, mixes tho new gas with tho coal-gas sup- 

 plied to the town in order to raise its light-giving power. The mains in the streets 

 are nearly five miles in length, and the gas is said to bear travelling through this 

 length of pipe very well. A considerable amount of cold is of course produced in tho 

 generator by the evaporation of spirit, but it does not follow that the farther cooling 

 of the gas will not condense some of the hydrocarbonous vapour. Farther experience, 

 therefore, is desirable to fully settle this point, though the homo manufacture of gas 

 in factories and large houses is a part of the inventor's scheme which does not entirely 

 depend for success upon the power of the gas to travel. The inn, a mile and a quarter 

 from the works, was lighted up on the occasion of a special trial during dinner, by 

 coal-gas and Kromschroder gas in turns, and the greater brilliancy of tho latter was 

 thus rendered strikingly evident, even after at least two miles' conveyance, and in 

 spite of a defect of pressure, arising from the hotel being at a ' dead end.' 



The inventor does not claim to bo able to supersede coal-gas in largo towns and 

 cities. He reckons that it may usefully and cheaply be applied to small towns con- 

 suming about a million cubic feet per annum, a consumption which would hardly 

 justify tho expense of erecting coal-gas works. The Great Marlow experiments have 

 confirmed tho confidence of himself and his co-workers in his system. Report made 

 to ' Iron: 



Messrs. Harrison are also tho patentees of an 'Air-Gas.' This process is very 

 simple, and consists merely in drawing air through light petroleum spirit, tho air 

 thereby becoming so charged with tho inflammable vapour of the spirit, as to burn 

 with a brilliant light. It is stated by tho inventors that tho mixture of air and 

 vaporised spirit is perfectly permanent, and can be stored in holders, or passed through 

 indefinite lengths of pipe, at varying temperatures, without suffering any condensation 

 or diminution of lighting power. This statement is somewhat difficult of In lie!, as 

 the gas produced by this process is a purely mechanical mixture, not tho least com- 

 bination (in a chemical sense) taking place, and there is every reason to think that 

 variations of temperature, such as must necessarily occur in tho ordinary distribution 

 of such a gas, would cause a partial deposition of tho petroleum spirit, and conse- 

 quently much loss of illuminating power. 



The air-gas invented by Mr. Wright, a plumber of Sheffield, must also bo noticed 

 here. His process is protected and involved by several patents: considerable mystery 

 is made of tho process by which his ' oil ' is obtained, but it is, of course, essentially 



