450 
ME. C. GEEVILLE WILLIA^IS ON SOIME OF THE PEODECTS 
Propyle 
C12 HU 
Boiling-pomt. Vapour-density. 
65° 2-98 
Per-centage of 
carton. 
83-72 
Per-centage of 
hydrogen. 
'16-28 
Butyle 
106° 
3-94 
84-21 
15-79 
Amyle 
C20 J^22 
158° 
4-91 
84-51 
15-49 
Caproyle 
C24 H^e 
202° 
5-88 
84-70 
15-30 
The boiling-points of the indifferent hydrocarbons being such important evidence, it 
has been considered proper to give positive proof that the fractions analysed were those 
whose constitution exactly talhed with the bodies with which they were sought to be 
identified ; in each case therefore the vapour-densities of several fractions near the known 
boiling-point of the radicals were determined ; and it is submitted, that it is no slight 
proof of the correctness of the view advanced relative to the nature of the bodies isolated, 
that in almost every instance the fraction which gave the coiTect vapour-density was 
that which corresponded in boiling-point with the radical. In order to save space, the 
numerous determinations made are condensed into Tables. In one or two of these 
merely trial experiments, it will be observed that the regularity of the series is slightly 
interrupted ; where this happens, it will be found to arise from the fact of the bodies 
not having been obtained from the fraction corresponding to their own boiling-point ; 
thus in the Table containing the amyle experiments, the fourth and sixth determinations 
are not in perfect harmony with the rest ; in the thud, the fraction used distilled between 
160° and 165°, but it was obtained from the portion of the crude hydrocarbons boiling 
between 150° and 160°; this makes the density come out somewhat lower than it would 
have been had the fraction been extracted from the hydrocarbons boiling between 160° 
and 165°. In general, however, it will be found that the increase of density with the 
rise of boiling-point is quite as steady as could have been anticipated. 
It has been stated that the composition of the fractions varied so little as the boiling- 
points became higher, that I did not imagine myself justified in consideiing the natui*e 
of any fraction established by the mere results of analysis ; but although vapoiu’-density 
has been chiefiy relied on as the means of research, it is believed, nevertheless, from the 
extreme care with which the combustions were made, that they represent very nearly 
the true per-centages of carbon and hydrogen. 
Chemists are aware that the accurate analysis of volatile fiuids, ha^•ing a high per- 
centage of carbon, is a somewhat fatiguing process, from the constant attention indis- 
pensable, and the slowness with which it is necessary to advance the fii’e along the tube. 
By the follomng method of burning, which is described in the hope that it may be 
found useful to others, less time and far less attention are requii’ed for the determination 
of the carbon and hydrogen in a body like propyle or butyle, than for the combustion 
of an ordinary solid. For this purpose the fluid is contained in one bulb, and is driven 
out at the commencement of the analysis into a column of thirteen or fourteen centi- 
metres of cold oxide of copper : this latter portion is never dii’ectly heated imtil the end 
of the analysis, the fluid being volatilized by the heat conducted by the oxide. Oxygen 
