and other Gnfcs afforded by Alcohol and Ethei: j ^ 



peculiar tendency to produce the olefiaiit gas, which property is wanting in the lime 

 and magnefia. Thefe different effefts certainly arife from a lefs degree of heat having 

 been applied in all the cafes where the olefiant gas was produced, and a greater in all 

 thofe which prefented the fimple carbonated hydrogenous gas. 



But the circumflance which is truly important for the general theory of fcience in thefe 

 experiments, is the new light they throw upon the formation of oil; and the force they give 

 to the notions already received and the confiderations long ago prefented in the pneu- 

 matic do£lrine, refpefting the nature and compofition of vegetable oily bodies. We here 

 fee that an oil is a compound of hydrogene, carbone, and a fmall portion of oxigeoe. We 

 find that, in the mixture of the olefiant gas, or denfe carbonated hydrogene, with the 

 oxigenated muriatic acid, an oil is immediately formed in the fame manner as when 

 wood, or any other vegetable matter, not in itfelf oily, is heated in a retort. It appears, 

 that the olefiant gas, or a gas very fimilar to it, is difengaged from wood, or any folid ve- 

 getable not of an oily nature, which is flowly burned. This gas, when burned in the 

 open air, depofits its foot or carbone, which blackens the wood, and clogs the channels 

 through which the elaflic fluid mull pafs. If wood, mucilage, Sec. be more fuddeuly and 

 ftrongly heated in clofe vefTels, they afford lefs oil, more coal, and more carbonic ncid ; and 

 in the open air there is more flame, and lefs coal or foot depofited. It is probable that, in 

 the firft cafe, the olefiant gas is difengaged, and in the fecond, the fimple carbonated hydro- 

 genous gas *. We are therefore in progrefs towards the artificial cor.ipofition of oil. 

 Nothing more feems to be required for its artificial produftion, than to obtain, without 

 vegetable matter, a denfe carbonated hydrogenous gas weighing 0.909, and to mix It with 

 the oxigenated muriatic acid gas: and we may hope to fucceed in the production of this 

 olefiant gas with mineral matters containing much carbone, fuch as certain kinds of fteel, 

 which when diflblved in an acid, by the decompofition of water they promote, afford a 

 difengagement of carbonated hydrogenous gas. This laft objeQ deferves all the attention 

 of chemifts, becaufe it opens a new path to the knowledge of vegetables, and particularly 

 of the formation of oil. 



The ingenious experiments of the Dutch chemlfts are among the few which afford 

 new profpefts to philofophers. Together with the difcoveries for which we are already 

 indebted to them, on the decompofition and recompofition of water by elei"tricity, on the 

 alkaline and metallic fulphures, &c. they will pofTefs a diflinguifhed rank in the pneumatic 

 chcmiftry, to the progrefs of which they have dedicated the reputation of their labours and 

 their difcoveries. 



• This excellent courfc of experiments, and the general imluflions founJed upon them, bring to my recol- 

 lection feme obfcrvations I had occafion to make many years ago, when alcohol was burned in the lamp of 

 Argand. In this experiment, the (Irata of ignited matter forming the interior and exterior flames (which have 

 not yet been accounted for) arc ftrikingly diftinft. I have fuppofed them to be referable to a general law of the 

 combudion of volatile matters at certain limits of temperature j as is mod eminently ietw in phofphorus and 

 fulphur, both of which have the two kinds of flame in fucceHion, and both begin ihcir flow combullion at very 

 m'jdcrate temperatures. But the faft immediately referable to the prcfcnt theory is this : When the lower 

 aperture or air palTage of the lamp is left open, the flame of the alcohol is as ufual faint and blucilh, rel'embling 

 that of carbonated hydrogene ; but if the paflTjge be gradually obftrufted by flowly applyini; the palm of the 

 hand, or any more fuitable obftacle, the flame becomes more and more luminous, like that of oil, until, in the 

 progrefs of obftruftion, the aperture is IV) much clofcd that the combuftion begins to decay for want of air. By 

 ■ proper adjuAment of the aperture, the alcohol may be made to burn with a conflantly luminous white internal 

 fiamc. In this cafe it may be fuppofed that the temperature is precifcly fuch as to extricate the olefiant gis. N. 



II. On 



