NAPHTHA, NATIVE 399 



and are commercially looked upon as one body. But as the similarity in the processes 

 of manufacture of both bodies must strike an intelligent workman, we need not feel 

 surprised when he calls alike the products of shale petroleum, or coal-tars from the 

 still naphthas. The distinction, moreover, is convenient ; as the products of the first 

 two bodies serve different technical purposes from the subsequent ones. They have 

 also become the subject of legislative provision on account of the lamentable accidents 

 whioh they have sometimes occasioned ; though the confusion in terminology is well 

 illustrated in a recent enactment which designates as petroleum all bodies from rock- 

 oil, schists, or peat inflaming below 100 Fahr. It has been generally thought that 

 the application of the term spirit would be a convenient substitute for shale or 

 petroleum naphtha. 



According to Wiederhold, crude or native naphtha gives by fractional distil- 

 lation : 



Petroleum gmrit <f 48 ' 6 P er Cent of 0<7 8 P ec> & rav> b Uin S at 100 Cent 

 \45-7 073 200 



Refined petroleum 57 0'80 above 200 



The lightest distillates of American petroleum, Sherwood oil, or shale have been 

 much investigated in regard to use as anaesthetics or as carburetters. Names ha* e 

 thus been given to the varied fractional distillates. Kleinschmidt of St. Louis 

 specifies the following : 



o o p o oBeanme. 



Oils distilling over below 377 specific gravity -0 '60 = 90-97 =Ehigolin 

 at 76'6 0'63 -0-61= 80-90 = Gasolin 



137'0 0-67 -0-63 = 70-80 = Naphtha 



148-0 0-73 -0-67 = 60-70 = Benzine 



183-219 0'78 -0'82 = 40-60 =Kerosen. 



The late Sir James Simpson took great interest in the anaesthetic powers of the first 

 series ; on account of them petroleum gained its healing repute amongst the American 

 Indians ; applied externally they soothe neuralgic complaints. 



Gasolin is mainly relied on as the carburetting agent by several new patent gas 

 companies who thus purpose to enrich common coal-gas, water-gas, or atmospheric air. 

 Spirit of specific gravity of about 0'650 and with a boiling-point of 58 Cent, is pre- 

 ferred for this purpose, and as this spirit, which the preceding analysis shows consti- 

 tutes so large an item in crude petroleum, is too dangerous to burn in common lamps, 

 it is sold at the price of a waste product. It is believed that one gallon of spirit 

 will carburet 500 cubic feet of gas, raising it in luminosity to 30 or 33 candle-power 

 of flame. The opposing elements of odour and danger may stand in the way ; but the 

 same process may be adapted in using this spirit for heating or smelting operations. 

 Mr. Wills, F. C. S. gives the following calculations founded on Dalton's law for ascer- 

 taining the vapour-tension of liquids. (' Journ. Soc. of Arts, No. 1070, vol. xxi.) 



Table of percentage of vapour of petroleum spirit of a specific gravity '650 present in 

 air or other medium at different temperature*. 



Temperature. Percentage. 



-10 Cent. (14 Fahr.) . 57 



(14 Fahr.) . 

 (32 ) . 



(32 ) . 10-7 

 10 (50 ) . 17-5 



Temperature. Percentage. 



-15 Cent. ( 60 Fahr) . 22-0 



20 ( 68 ) . 27-0 



40 (104 ) . 39-0 



This diffusibility through air in the state of vapour of petroleum has occasioned 

 many lamentable accidents, to prevent which various legislative measures have been 

 passed. When a light is applied to a common paraffin-oil lamp, in which the oil 

 is at once converted into vapour, ignition will occur. Explosion will also supervene 

 on shipboard or in a room, in which a mixture of common air and hydrocarbon- 

 vapour, whether from low specific gravity, or from the construction of the reservoir- 

 ceil, have been allowed to accumulate in the proportions which cause coal-mine or 

 domestic gas mixed with air to explode. Petroleum and the paraffin oils alike 

 consist of a series of oils bound together by links and very similar in composition. 

 But the first members of the series are very easily detached from the others, and 

 their vapours come off at ordinary temperatures. Mere specific gravity does not, as 

 was once thought, determine the safety of an oil. The specific gravity of mineral oil 

 ranges from 814 to 830, the extreme point at which it easily ascends a wick 

 without charring it. But petroleums of 800 have been shown perfectly safe by tho 

 tests of flash-point and firing- point ; whilst others standing at higher numbers on 

 the hydrometer liavo not stood them. In America the original way of testing the 

 firing-point of oils is by placing a light in the open vessel containing them, which is 

 being also heated, and noting the exact degree on a thermometer whose bulb is also 

 immersed in the fluid, when flame appears on its surface. In this country, again, 



