362 PEINCIPLES OF CHEMISTKY 



tricts as, for instance, by the slopes of the Caucasian chain, on inclines 

 in a parallel direction to the chain an oily liquid issues from the earth 

 together with salt water and hot gases (methane and others) ; it has a 

 tarry smell, dark brown colour, and is lighter than water. This liquid 

 is called naphtha or rock oil (petroleum), and is obtained in large quan- 

 tities by making wells and deep bore-holes in those places where traces 

 of naphtha are observed, the naphtha being sometimes thrown up from 

 the wells in fountains of considerable height. 52 The evolution of 

 naphtha is always accompanied by salt water and marsh gas. Naphtha 

 has from ancient times been worked in Russia in the Apsheron penin- 

 sula near Baku, and is also now worked in Burmah (India), in Galicia 

 near the Carpathians, and in America, especially in Pennsylvania and 

 Canada. Naphtha does not consist of one definite hydrocarbon, but of 

 a mixture of many, and its density, external appearance, and other 

 qualities vary with the amount of the different hydrocarbons of which 

 it is composed. The light kinds of naphtha have a specific gravity about 

 0'8 and the heavy kinds up to 0*98. The former are very mobile liquids, 

 and are more volatile ; the latter contain less of the volatile hydro- 

 carbons and are less mobile. When the light kinds of naphtha are dis- 

 tilled the boiling point in the vapours constantly changes, beginning at 

 and going up to above 350". That which passes over first is a very 

 mobile, colourless ethereal liquid, from which the hydrocarbons whose 

 boiling points start from may be extracted namely, the hydrocarbons 

 C 4 H 10 , C,H 12 (which boils at 30), C 6 H U (boils at 62), C 7 H 16 (boils- 

 about 90), tkc. Those fractions of the distillate of naphtha which boil 



the main part (Lisenko, Markovinkoff, Beilstein), but doubtless (Mendeleeff) it also con- 

 tains saturated ones, C M H.,,, l+ . 2 . The structure of the naphtha hydrocarbons is only known 

 for the lower homologues, but doubtless the distinction between the hydrocarbons of the 

 Pennsylvania!! and Baku naphthas, boiling at the same temperature (after the requisite 

 refining by repeated, methodical distillation, which can be very conveniently done by 

 means of steam, passing the steam through the dense mass that is, by means of rectifi- 

 cation), depends not only on the predomination of saturated hydrocarbons in the 

 former, and naphthenes, C,, IL n , in the latter, but also on the diversity of composition and 

 structure of the corresponding portions of the distillation. The products of the Baku 

 naphtha are richer in carbon (therefore, in a suitably constructed lamp they ought to give- 

 a brighter light), they are of greater specific gravity, and have greater internal friction 

 (and are therefore more suitable for lubricating machinery) than the American produsta 

 collected at the same temperature. 



52 The formation of naphtha fountains (which burst forth after the higher clay strata, 

 covering the layers of sand impregnated with naphtha have been bored through) is with- 

 out doubt caused by the pressure or tension of the combustible hydrocarbon gases 

 which accompany the naphtha, and are soluble in it under pressure. Sometimes these 

 naphtha fountains reach a height of 100 metres for instance, the fountain of 1887, near 

 Baku. Naphtha fountains generally act periodically, and their force diminishes with the 

 lapse of time, which might be expected, because the gases which cause the fountains find 

 an outlet, and the naphtha issuing from the bore-hole carries away the sand which was, 

 partially choking it up. 



