1820.] Accum on Coal Gas 2$^"},. 



The InKer sort nf coke is iiiiqtieslionably preferable for the smelter, and Jill 

 furnace operali.iiis, standing (lie l)l:ist of the bellous well. But ihe coke produced 

 in the new mode of operaiinir is betier suited for liie great mnjority of dotneHtic 

 purposes, kindlii'g more readily, and making a more cheerful lire. The combustion 

 of tlic dense, or as it is now called, cylinder coke, can be only kept uj) w liCii Used 

 in a eoiiiinon grate, by a strung draft of air ; and it is, therefore, not so well suited 

 for fuel for domestic purposes, to ii:ake a suial! fir,' ; bill tlie coke oblaiiu'd by the 

 horizontal rotary retort readily maintains its own combustion, even wiicn in small 

 masses; hence it may be Used viithou: any trouble, either in the fire-place of the 

 cottager, or oftlie prince, and accordingly it bears a higlierprice in ihenuirket. 



I may venture to suggest a suspicion that the gas obtained by 

 this apparatus will yield less Hght than when it is obtained in the 

 usual way. My reason for the suspicion is the quantity of tar 

 decomposed by it. Now in all my own trials to decompose the 

 tar, the gas obtained burned very badly. 



The object-of the eighth part is to explain the contrivances 

 fallen upon to sepa.rate tlie sulphuretted hydrogen gas fromthe coal. 

 This is done by causing the gas to pass through a milk of lime ; 

 and about two per cent, of lime to the gas produced has been 

 found sufficient to purifj' it when properly applied ; for the inge- 

 nious contrivances tha,t have been adopted to ensure the purifi- 

 cation of the gas, I must refer the reader to the book itself, as, 

 in order to be understood, they would require to be elucidated by 

 plates. 



The ninth part is occupied v,'ith descriptions of the gasholders, 

 and with the very ingenious improvements of Mr. Clegg upon 

 this most esseiitial part of the apparatus. His governor, his 

 reciprocating safety valve, and his various modifications of the 

 gasholder, deserve the particular attention of every person who in- 

 tends constructing an apparatus for procuringlightby means ofgas. 



The tenth part is employed in descrilnng the gas meter, a very 

 ingenious contrivance of Mr. Clegg, by which the quantity of 

 gas formed and the quantity given out to the consumer may be 

 accurately measured. I can only notice the subjects treated of. 

 From the nature of each it would be impossible to convey an 

 accurate notion of them to the reader without transcribing the 

 descriptions and giving the pb.tes ; that is to say, without giving 

 almost the whole of the book. 



The remaining part of the book is employed in describing the 

 regulating gauge, the gas mains anabranch pipes, the gas lamps 

 and burners, the illuminating power of t'ne gas, and the quantity 

 of it consumed in a criven time. To o'ive the reader an idea of 

 this very essential datum, we quote the following paragraph: 



The following slatc.iient exiiibits t!ie cjuanlity of coal gas consumed in a given 

 time by diUVrenl kinis of arg.ir.d lamps. Anaigaiid burner which measures in tiie 

 upper rim half an inci) in diamelei, beti'pen lue holes from « liidi the gas issues, 

 wlien furni.died witli live apertures one twenty-iifth part of an inch in diameter, 

 consunii'b two cubic fi'et ofgas in an hour, when ll* gas flame is one and n. half 

 inch high. Tiie illuminating power produced by this burner it eijuai to tiiree 

 tallow caiidKs eight in the pound. 



An argand burner, three ()uariers of an inch in diameter between Ihe holes in the 

 upper rim, iind peifora:ed with holes, ono-thiitielh of an inch in dia'neter, con. 



