CAR
CAR
( 91 )
with 500. of oxygen deprived of carbonic acid,~~but containing 2 3.5 of azote. The mixedgasses were reduced by the detonation to 409.5parts, from which potash extracted 201. ofcarbonic acid, and hydrosulphuret of potash184.5 of oxygen, leaving 24 parts of azote.Hardly of the olefiant gas escaped com-bustion, for, on adding a known quantity ofhydrogen to part of the entire residue of thedetonation and again exploding it, the diminu-.tion was scarcely more than would have beenproduced by adding the hydrogen alone, andsufficient oxygen.
By subtracting the oxygen of the carbonicacid produced in this experiment from theentire quantity consumed, and finding the■weight of hydrogen, required to convert thisremaining oxygen into water, the author findsin 100 parts, by weight, of olefiant gas, 84.78of carbon and 13.55 of hydrogen, reckoning27.2 of carbon in 100. of carbonic acid. Thiscomputation leaves only 1 .67 of the 100. partsof olefiant gas unaccounted for, which is quitewithin the limits of unavoidable errors ; for, inanother experiment conducted in the same way,the sum of the carbon and hydrogen a littleexceeded the olefiant gas employed. HenceM. de Saussure concludes that pure olefiantgas, in the preparation of which the distillationhas not been carried too far, contains no oxy-gen, but is composed simply of about 86. ofcarbon and 14. of hydrogen, proportions whichagree very closely with those of Dalton andThomson. The specific gravity of this gaswas about .985, common air being 1.000. If15 parts by weight of hydrogen condense tohalf their volume by dissolving 85 parts ofcarbon, the resulting olefiant gas would by cal-culation, be found to have nearly the abovespecific gravity.
It has been mentioned in the original article(Ch. Diet. vol. 1, p. 257) that when olefiantgas is exploded with little' more than its own
bulk of oxygen, so much carbon is precipitatedin substance as entirely to blacken the vessel.Dr. Thomson has repeated this experiment,employing rather less oxygen than olefiant gas.After the explosion, the bulk of the residueis much greater than that of the gasses beforeexplosion, being increased in about the propor-tion of 16 to 10. ; or in still greater propor-tion if the uncombined oxygen that remainsin the residue be removed. This residuarygas is much lighter than olefiant gas, havingthe specific gravity of only 0.48, and is con-sidered by Dr. Thomson as a proper oxjjcar-b u retted hydrogen, or triple compound ofoxygen, carbon, and hydrogen, and the pro-portions would nearly indicate the combinationof an atom of each of these elements.
A great number of interesting experimentshave been made at different times by Dr. Henry,on all the above described inflammable gasses,more particularly with a view to direct theeconomical use of the gas procured from thedistillation of coal, which has now becomean object of considerable national importance.Dr. Henry’s first series of experiments, thoughconfessedly imperfect, requires a short notice inthis place.d Dr. Henry constructed an Argaudlamp* to be supplied with gas instead of oil,and found that both pure hydrogen and car-buretted hydrogen, from moist charcoal, andcarbonic oxyd, gave so trifling a light as to beentirely unfit for the purposes of illumination ;while on the other hand the gas distilled fromcoal, gave a light little inferior to that fromgood spermaceti oil. Neither is this differencematerially owing to any oily matter mechani-cally suspended in the coal gas, since it retainsits power of burning with a bright dense lightafter being long kept over water, though some-what impaired in intensity. The followinggasses were then burnt with oxygen in closevessels, and the comparative quantities requiredfor saturation were noted.
Pure Hydrogen
50
— — 0 .“
Gas from moist Charcoal
60
-- 35.
-- Wood
54
33.
- dried Peat
68
43.
--Caunel Coal
170
— 100.
Lamp Oil
1*90
124.
Wax
220
137.
Pure Olefiant Gas
284
179.
M 2
/V
* Phil. Jovtm. vol. xi. p. 65.