MABERY. — ON THE COMPOSITION OF PKTROLEUJI. 347 



for thirty days. The change was shown by the increase in spocific 

 gravity : 



Specific gravity at 15° 

 befoie exposurn. 



Dec. 9. Dec. 12. Jan. 8. 



0.000 0.840 0.862 



When taken from the fine, January 8, the residue weiglied one kilo, 

 which sliowed a loss of GG.G7 per cent. The original oil distilled as 

 follows : 



50^-150^. 1.50^-200^. 200^-250^. 250='-300^. +300'^. 



21 percent. 11 percent. 11 percent. 13 percent. 42 percent. 



The residue above 300° is, therefore, about the same in weight as the 

 residue left by evaporation. That the loss by evaporation had practically 

 ceased at the end of one month was shown by allowing the residue to 

 stand one year in the same place, exposed to draft as before. But there 

 was no change in weiglit nor in specific gravity. 



A combustion of the crude oil gave the following percentages of carbon 

 and hydrogen : 



0.19G8 gram of the oil gave 0.4915 gram COo and 0.2512 gram H2O. 



C 85.51 



H 14.18 



Combustion of the residue after 30 days' evaporation : 



0.1559 gram of the oil gave 0.4925 gram CO., and 0.1559 gram H2O. 



C 86.16 



H 13.69 



Evaporation of the portions with lower boiling points, which form 

 the greater part of the series Cnli-2n+2i leaves a larger proportion of series 

 poorer in hydrogen, CqILq and CnIl2n-2 corresponding to the composition 

 shown by analyses. 



On cooling with ice the residue from evaporation became quite solid. 



On distillation, 28 per cent came over below 30°, 6 per cent at 300^- 

 360', with a residue above 3G0° of 66 per cent. 



The amount of solid hydrocarbons in the residue was determined by 

 the method suggested by Zalioziecki. 50 grams of the residue with fusel 

 oil, mostly isoamyl alcohol, was allowed to stand at 0° for 24 hours; 

 250 grams alcohol was then added and the precipitate collected on a 



