WOOD AXD PEAT GAS.] 



UNDULATORY FORCES. LIGHT. 



125 



cannel produces, in the usual way, 10,500 cubic feet of 

 forty-candle gas; bnt with the hydro-carbon process it 

 will yield 36,000 cubic feet of twenty-candle gas, or 

 68,000 cubic feet of twelve-candle power; and a ton of 

 Boghead, which generally furnishes about 13,500 cubic 

 feet of forty-candle gas, will by this process give as much 

 as 52,000 cubic feet of twenty-candle gas, or 75,000 of 

 twelve-candle. From which it is manifest that, although 

 there is a comparative reduction of the illuminating 

 power in consequence of the diluting power of the water- 

 gas, yet, on the whole, there is a considerable increase in 

 the amount of illuminating material. This increase 

 varies from 50 to 100 per cent. ; and it is, no doubt, due 

 to the property which water-gas has of suspending the 

 volatile hydro-carbons which are generally condensed in 

 the tar. 



Mr. Clegg states, that the cost of working the process 

 is not very considerable, for gas of twenty-candle power 

 may be obtained from Wigan coal at the rate of Is. 3|<i. 

 per 1,000 ; from Lesmahago at 11 Jd. ; and from Boghead 

 at lid. : besides which, the gas is remarkably free from 

 every kind of sulphur compound. The conclusions at 

 which Dr. Frankland has arrived, after having made a 

 very careful examination of Mr. White's process, are the 

 following : 



1st. That it greatly increases the produce of gas from 

 a given weight of coal, the increase being from 4C to 290 

 per cent. , according to the nature of the material operated 

 U] op. 



That it greatly increases the total amount of 

 illuminating power, the increase being from 12 to 108 

 per cent. 



3rd. That it diminishes the quantity of tar formed, by 

 converting it into gases of high illuminating power. 



4th. That it affords a means of reducing the illumi- 

 nating power of gases which could not be profitably burnt 

 alone : and, 



5th. It may be easily applied to any of the apparatus 

 or modes of working now in use. 



In opposition to these conclusions must be placed the 

 results obtained by Messrs. Braude and Cooper, who 

 found that little or no advantage was gained by the pro- 

 cess ; and Dr. Fyfe, who is much opposed to the whole 

 scheme, states that, when all tilings are considered, it is 

 a process which ought at once to be abandoned. Mr. 

 Barlow has, however, recently examined the merits of 

 the process ; and he believes that, with some few altera- 

 tions in the way of working, it may be profitably carried 

 out. His suggestion is to collect the watur-gas in separate 

 gasometers, and to convey it from them, instead of from 

 the retorts, into the compartments where the coal is dia- 



t i I i i r . _,'. 



Water-gat alone. Several patents have been taken 

 out, at various times, for the production of ^f, from 

 water, and for the employment of such gas either alone, 

 as when it is wanted for heating purposes, or in combi- 

 nation with the vapour of naphtha. Donovan's patent, 

 of 1830, we have already alluded to. M. Floret has 

 contrived an arrangement for decomposing steam, by 

 means of coke heated to a high temperature in an at- 

 mosphere of oxygen. Mr. Paine, of America, says he 

 decomposes water by the aid of electro-magnets; Mr. 

 Adams, of Boston, effects it by the force of a galvanic 

 battery ; and Mr. Shepard assists the action by using a 

 salt of ammonia, or a vegetable acid, as the oxalic. In 

 Hr. (iillard's process, steam is decomposed by passing it 

 ulescent charcoal, in such a manner as to form 

 hydrogen and carbonic acid ; the latter being abso: 

 in the usual way by means of caustic lime. All ti 



its, however, are but so many examples of fruitless 

 speculation ; and they may be pointed at as illustrat 

 of so-called unsound chemical knowledge, combined with 

 the worst kind of practical experience. 



As the hydrogen and carlxmic oxide produced by 

 either of these processes does not possess the smallest 

 amount of illuminating power, it mast bu brought up to 

 the required standard, either by passing it through a 

 volatile hydro-carbon, or by burning it in such a way as 

 to make a solid incombustible body wliite-hot. Mr. 



Gillard adopts the latter contrivance ; and his plan is to 

 consume the gas from an Argand burner, over which 

 there is suspended a rosette of platinum wire. The wire 

 becomes intensely heated ; and, when the gas is burning 

 at the rate of six-and-a-half cubic feet an hour, the light 

 emitted is about equal to five composite candles, or to 

 that of a fish-tail consuming three feet of ordinary gas 

 per hour. 



Wood Gas. When wood is subjected to distillation in 

 closed iron vessels, it evolves a large quantity of inflam- 

 mable vapour, some of which condenses into a liquid form, 

 while the rest passes off as combustible gas. The liquid 

 consists of water, pyroligneous acid, naphtha, and a com- 

 plex heavy tar ; and the gas is composed of hydrogen, 

 carbonic oxide, carbonic acid, light carburetted hydrogen, 

 and a variable proportion of olefiant gas. When these 

 are consumed in the ordinary way, they do not produce 

 much light; but if they are passed through a volatile 

 hydro-carbon, they may be brought up to any degree of 

 illuminating power. It is possible, also, that by certain 

 modifications of the process whereby they are obtained, 

 a sufficient amount of rich hydro-carbons may be gene- 

 rated, to do away with the necessity for subsequent 

 naiihthalisation. Mr. Hills proposed to mix the gases 

 which are obtained during the manufacture of crude 

 pyroligneous, with those which result from the destructive 

 distillation of coal-tar; and Mr. Lowe has taken out a 

 patent for the use of tar, oil, resin, or cannel coal, as a 

 means of giving illuminating power to the gases evolved 

 from sawdust, spent bark, or peat. Other patentees have 

 suggested that the sawdust and tar should be mixed 

 together before they are distilled ; but it does not appear 

 that any of these schemes have been successful in practice, 

 or have been able to compete with the more economical 

 mode of obtaining gas from coal. On the continent, 

 however, where wood is very abundant, and coal scarce, 

 it is frequently more profitable to make gas from the 

 former tlian from the latter. At Bale, for example, and 

 some other towns of Switzerland, Norway, and Sweden, 

 the process of distilling gas from wood is practised 011 a 

 very large scale. We are told that the old city of lleil- 

 bronn has recently been lighted up with wood-gas ; the 

 manufacture of which is under the management of M. 

 ifelen, who produces a gas of very good illuminating 

 power. It is said that a fish-tail burner, consuming 

 four-and-a-half cubic feet per hour, gives the light of 

 thirteen wax candles ; and that one of five cubic fuet an 

 hour, produces the light of sixteen candles ; while an 

 Argand burner, on Dumas' construction, consuming the 

 same amount of gas, evolves the light of twenty candles. 

 If this be so, it is evident that wood-gas can be obtained 

 of a quality superior to that of ordinary coal gas. 



Peat Gas. This is nearly of the same composition as 

 the gas evolved from wood ; and the collateral products 

 are nearly of the same description and value. Many 

 chemists have, at different times, devoted their attention 

 to this subject; but it is only very recently that precise 

 information has been obtained concerning it. Sir Robert 

 Kane in Ireland, and Dr. Letheby in England, have 

 each reported on the quality of the products generated 

 during the destructive distillation of peat; and from 

 ;heir statements it appears, that 100 parts of peat will 

 furnish from 10 to 40 of charcoal, from 2 to 5 of tar, 

 Tom 1 1 to 38 of aqueous matters, and from 25 to 58 of 

 jas. The charcoal is very valuable as a decolorisor and 

 disinfectant; the tar is rich iji ] arallino and creosote; 

 ;he watery fluids contain ammonia, acetic acid, and wood- 

 i.iphtha; and the gases consist of hydrogen, carbonic 

 . carbonic acid, and various hydro-carbons. One 

 .housand parts of peat will yield, on an average, 2 '7 of 

 ammonia (equal to 10'4 sulphate), It) acetic acid, 1'4 

 wood-naphtha, 7'!' volatile oils, 6 '5 fixed oils, and 1'4 

 nraffine. From Dr. Letheby's experiments, it appears 

 hat a ton of peat will furnish about 13,000 cubic feet of 

 gas, the illuminating power of which is equal to seven 

 tatidanl candlus, when the gas is burned from an Ar- 

 ;and that consumes five cubic feet per hour ; but the 

 ntunsity of the light may be brought up to any degree 

 >y the usual process of najihtlmlisation. As peat is 



