200 EXAMINATION OF A NAPHTHA FROM LBIE-SOAP. 



08882 grm. carbonic acid (I). Another portion, not weighed, gave 0.18 grm. water and 

 0.513* grm. carbonic acid (II.). 



Found. 

 I. II. 



Carbon 87.46 87.51 

 Hydrogen 12.47 12.49 



99.93 100.00 



From these results we derive the formula C 18 H 154 . It appears, then, that this 

 -purious heap is composed in great part of a member of the benzole series, — undoubt- 

 edly of the one which boils at 170° (isocumole) ; indeed, the formula last given is much 

 nearer that of isocumole than the one previously derived from an analysis of the. frac- 

 turn 1G*>°-166°. During the redistillation of the intermediary fractions the volatile 

 matter, which, as fast as it was eliminated from the products 165°-173°, had been 

 heaped up at the upper extremity of the intermediary series [namely, at 163°-164°], 

 gradually came forward towards its own proper place at 153°, or thereabouts, and in 

 o doing dragged along with it a quantity of the isocumole properly belonging at 170°, 

 until a point was reached at which the tendency of the isocumole to go back nearly 

 balanced the power of the 153° body to go forward, and at this point a temporary heap 

 of course arose. At the moment of the analysis, this heap had been operated upon so 

 long that the isocumole was largely in excess ; but if an analysis had been made of the 



* 



heap as it existed a week earlier, a different result would undoubtedly have been ob- 

 tained. 



Such temporary adjustments, or, as it were, balancings of the opposing forces exerted 

 by two bodies of different degrees of volatility, are noticed not unfrequently in the 

 course of the earlier series of distillations of a mixture of crude hydro-carbons. Soon 

 after definite heaps first begin to appear, there will be seen for a time, at points about 

 midway between the real, permanent heaps, small temporary elevations, which subse- 

 quentlv disappear again as the distillation progresses. But as at this stage of opera- 

 tions all of the fractions are far from possessing constant boiling points, no question as 

 to the lack of individuality of these half-way heaps can well arise. It is probable that 

 the danger of mistaking a counterfeit for a real heap can only occur by virtue of some 

 such cause as in the instance above cited, or where one of the components of a mixture 

 of two bodies is in large excess as compared with the other. Perhaps the substance 

 encountered by Pelouze and Cahours* at 136°-138°, and described by them as hydride 

 ot pelargyl = C 18 H20, may have been nothing more than a spurious heap, such as 



* Bulletin de la Soctfte Chiraique de Paris, 1863, pp. 235, 238. 



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