MR. HENRY OtJ COMBUSTIBXE GAS'ET. f^^ 



Vj of oxigen, are found after combuftion. Now, according 

 to Mr. Cruickftlank, thefe 35 m. of carbonic acid, if formed 

 frona carbonic oxide, would require only 15 additional mea- 

 fures of oxigen gas, which is not very remote from the truth. 

 Keafoning in the fame mode, the gafes from wood and from peatGafes from 

 will appear to be mixtures in different proportions of two ^t '^^"^"^'^^^IJ^^^^^^^^ 

 leaft of the above-mentioned, viz. hydrogen, and the carbo-of uncombined 

 iiic oxide. The refults of the combuftion of the gafes from 'nflammable 

 wood and peat evince that they differ confiderably from that^oal gas, 

 obtained from coal; and contain much lefs uncombined in- 

 flammable matter. Another circumftance of dillin6tion alfo 

 is, that, before being waftied with lime-liquor, the gas recently 

 prepared from wood or from peat, contains from | to i its bulk 

 of carbonic acid ; whereas the gas from coal lofes by this ab- 

 lution only, from ^y to ^V* * I^ ^^y ^^^ experiment, I found 

 a large admixture of azote in all thefe gafes; but this after- 

 wards proved to be accidental and not eflfential ; fince by care- 

 ful diftillation in glafs retorts, of the fubflances that afforded 

 ihein, the gafes were obtained entirely free from this conta- 

 mination* 



The gafes obtained by the deftrudive diftillation of oil and The gafes from 



of wax, it mav be obferved in the table, confume confider-°'' ^"'^ ^'■'''" 

 ■' . wax are pure 



abJy more oxig^n than the gas from coal. This circum[!ahce hydro-carburets, 

 firft led me to fufpea that they might poffiblv be mixtures of^/<^<^?^^^^^ the 



I 1 r • . , . 1 . , . fi'"'^ contains 



the plehant gas with carburetted hydrogen; and on apply- one-eighth and 



iiig the oxygenized muriatic acid gas, this fufpicion was fullv^^^ latter one- 



■c J r\ r r .L c -i • i r i "' f'^urth of defiant 



veritied. One meatare ot the gas from oil with one of theggg^ 



oxygenized gas, were reduced ("peedjly to If ; a like diminu- 

 tion was produced in the gas from tallow; and that from wax 

 had its bulk ftill further contracted, only If ra. being left by 

 ■iimilar proportions. 



*The condenflble ■pradii6ls alfo of coal probably differ from thofe 

 of wood and peat. If an intermediate veflel be placed for their 

 reception, it emits, after tlie diftillation, a ftrong fmell of ammo- 

 nia. This was long ago obferved by Lord Dundonald, who enu- 

 merates, among other produfts of coal, the volatile alkali (fee a 

 pamphlet " on the Ufes and Qualities of Coal Tar," pnblifhed by 

 his Lordfliip in 1785.) This produilioh of ammonia I have not. 

 obferved frohn peat or wood ; nor do I find it mentioned in a Hif- 

 tory of Peat, including the refults of its diftillation, &c. publiftied 

 m the fecond voUof the Edinburgh " EiTays Phyficai and Literary." 



5 In 



