MABERY. — ON THE COMPOSITION OF PETROLEUM. 301 



VII. COMrOSITION OF COMMERCIAL VASELINE, COSMOLINE, 

 AND SIMILAR PRODUCTS. 



After ascertaining the composition of the constituents of Pennsylvania 

 petroleum with high boiling points, and the composition of the semi- 

 solid product used at Coreopolis for the maiuitacture of the medicinal 

 preparations, it seemed of interest to investigate the composition of the 

 commercial products for comparison with specimens obtained directly 

 from the wells. On account of the very high boiling points, it is only 

 possible to apply distilhition in vacuo. Under 15 mm., 100 grams of 

 vaseline (Ceroleum) distilled in the following proportions. 



-250= 250^-275° 275^-300° 300-'-325^ 325-350^ 3:0^-360o Kesklue. 



Grams 14 22 14 18 7 20 6 



The distillates were light yellow in color, and when melted showed a 

 slight fluorescence. Below 250° the distillate was a heavy viscous 

 liquid, the others all semi-solid, and the residue was colored brown. To 

 ascertain whether solids could be separated from these distillates, tiie 

 fraction 250^-275° was dissolved in ether and sudirient alcohol added to 

 precipitate the solid hydrocarbon. The solid was again dissolved in 

 ether and precipitated by alcohol. After filtration it showed no greasy 

 feel and melted at 70^^. After similar treatment, from tl.e fraction 

 350^-360°, a solid was obtained which melted at 77° -78°. These solids 

 resembled in all respects the solid parafline hydrocarbons. It is there- 

 fore evident that vaseline is composed of heavy oils such as have been 

 identified as forming the portions of Pennsylvania petroleum with high 

 boiling points, and Coreopolis heavy oil, hydrocarbons of the series 

 C„IIon, CnII.2n_2, and CJ^l^n^, together with solid paraffine hydrocarbons. 

 The quantity of solid compounds present is sufilicient to saturate the oil 

 and in slight excess to form an emulsion of the desired consistency. 



What is known as "scale" paraffine in the refineries is composed of 

 the solid hydrocarbons, with enough of the heavy oils to form a greasy 

 solid. But the solid constituents are hydrocarbons of the same series, 

 CnH2n+2> which Cannot be changed into other forms without decom- 

 position. These hydrocarbons are only sparingly soluble in the liquid 

 hydrocarbons of lower boiling points of the same series; but they 

 dissolve more freely in the series with high boiling points, C„H2n+2, 

 C„TT„„, C„H2„_o, and" CJl2„_4. 



Since the work described in these papers was begun, ten years ago, I 

 have received efficient aid from the following assistants in distillation : 



