CHAPTEE XVIII. 



DERIVATIVES OF CAHBON (CARBON COMPOUNDS) —PRODUCTS DE- 

 RIVED FROM TIIR FATTY SERIES— PETROfiEU.M fliURXIXG OIL)— 

 PETROLEUM SPRAYS— PETROEEUM OIE EMULSIONS- PETHOLEUM- 

 SOAP EMULSIONS— PETUOLEEM SPIRIT— VASELINE— ACETYLENE. 



iio. Petroleum. — Natural Occurrence. — Petioleum is a natural 

 mixture of all the formeuic hydrocarbides.^ They are found to^^ether 

 in these mineral oils from butane, even from ethane aijd propane to 

 hexadecane. All these hydrocarbides are normal in structure without 

 lateral chains, as C"H2" + ^. But the composition of these petroleums 

 is i\ot everywhere the same. American petroleums contain, besides 

 saturated hydrocarbides of the formulae C"H^" + ^, some non-saturated 

 hydrocarbides of the series C"H^", as well as a little cumene and 

 mesitylene. Caucasian petroleum consi-ts of polymethylenic hydro- 

 carbides. Petroleum forms large subterranean sheets w^hich constitute 

 naphtha (crude oil) and which are w-rought by means of wells. 

 Petroleum is found in Alsace in the departments ot Herault and Isere, 

 at Saint Boes in the Lower Pyrenees, in Dauphine, etc. The origin 

 of these sheets [of petroleum] is due to the subterranean decomposition 

 of vegetable remains or to the action of w^ater at high temperatures 

 on metallic carbides, such as carbide of iron, which exists in subgranitic 

 regions. At Smyrna petroleum issues, in fact, from granitic ground 

 itself, below which there cannot be deposits of coal or organic matter. 



Fe,C + 2SiO, + 2K,0 = 2FeOSiO, + CH,. 



Commercial Products. — In the industiy the petroleums are 

 separated by [fractional] distillation and classed according to their 

 volatility thus : — 



1. Pe^ro/eww^^/zers.— Hydrocarbides, B. P. 0°-70°C. ; D. =0-600- 

 0*650. Consist especially of pentane and hexane. 



2. Petroleum spirit (commercial ligroin), B.P. 70''-120° C. ; 

 D. = 0-650-0-720. Consist especially of heptane and octane. 



3. Petroleum oil (burning oil, photogene), B.P. 120"-280° C. ; D. = 

 0-750-0-820. 



4. Heavy petroleum oils, B.P. 280°-380° C. ; D. = 0-820-0-870. 



5. Crude paraffin wax (paraffin scale), M.P. 30^-65" C. ; B.P. 

 170°-254° C. ; D. = 0-900-0-950 from C,-H.,,, to C,,H^.,. 



6. Vaseline, unctuous, inodorous, unoxidizable grease, M.P. 30"- 



1 Trri?isl(ii()r's NoIp. — Known to us as the marsh f,'as or paraffin series, but 

 to the disciples of Berthelot as the fornienic hydrocarbides. 



(294) 



