226 Messrs. Wanklyn and Cooper on 



are not correctly described as being fractions, but are properly 

 termed the fractionation-products. 



The American Petroleum upon which we have operated is 

 a most abundant commercial article. We found the sp. gr. 

 at 18° C. to be 0*7924. Tested with slightly diluted sulphuric 

 acid it did not diminish in volume. A preliminary experiment 

 in the retort showed that its distillation covered a great range 

 of temperature. Thus, in operating upon a charge of 600 

 cubic centim. and distilling into graduated measuring-glasses > 

 we made the following readings of thermometer and dis- 

 tillate : — 



At 157° 



distillation began. 









Up to 170° 



distillate 



measured 



50 cubic 



centim. 



>, 184° 



V 



V 



100 



v 



jj 



„ 196° 



V 



J' 



150 



» 



?? 



„ 209° 



?? 



V 



200 



J7 



?? 



„ 227° 



V 



V 



250 



JJ 



v 



„ 247° 



)3 



V 



300 



J? 



V 



„ 264° 



JJ 



)) 



350 



)) 



?' 



„ 270° 



J? 



J) 



360 



V 



?J 





Residue ] 



n retort = 



240 



»» 



<1 



The original liquid upon which we have carried out this 

 investigation was in this manner shown to be of such a nature 

 as to rise 90 degrees Centigrade in yielding half of its 

 volume of distillate, and to yield nothing at all below 157° C. 



Our actual operation was carried out on a considerable 

 scale, and our fractionation-products are as follows : — 



There is first of all a small proportion of very volatile 

 liquid, the fractionation of which we have not yet attempted, 

 but which we expect to fractionate on a future occasion. This 

 most volatile lot amounts to about one per cent, of the ori- 

 ginal petroleum. Then we have seven fractionation-products, 

 amounting on an average to 3'06 per cent, of the original 

 petroleum. Each of these seven fractionation-products is a 

 single chemical substance of sufficient purity for proper iden- 

 tification. As we have mentioned, these substances obtainable 

 from American petroleum were shown by Cahours and Pelouze 

 to be members of the same family as Marsh -gas. Adopting 6 as 

 the atomic weight of carbon, the formula of Marsh-gas becomes 

 C 2 H 4 ; and taking CH = 7 as the common increment of the 

 series, we have C 2 H 4 ; C 3 H 5 : C 4 H 6 as the second, third, and 

 fourth terms. 



Our seven hydrocarbons extracted from American petroleum 

 have the following formulae : — 

 Cj5H 17 j C 16 H 18 ; C 17 H ]9 ; G 18 ii 20 ; G 19 H 21 ; C 20 H 22 ; and C 21 H 23 . 



We propose to name the members of the series as follows: — 

 C 15 H 17? Marsh xv. ; C 16 H 18 , Marsh xvi. &c. 



Tabulating our results we arrive at the following : — 



