150 THE POPULAR SCIENCE MONTHLY. 



gases and volatile liquids giving off at ordinary temperatures gases, 

 which form explosive mixtures with air; heavy oils, which injure its 

 burning properties, but are useful as furnishing lubricators and paraf- 

 fine ; tarry and carbonaceous matters ; sulphur and other compounds, 

 which give an offensive odor when burned. It is therefore refined by 

 distillation, to separate the useful products in a pure state. The general 

 features of the process will be best illustrated by a practical example, 

 and for this purpose we have selected the well-known refinery of 

 Charles Pratt & Co., at Greenpoint, Long Island, manufacturers of 

 Pratt's Astral Oil. This establishment has a capacity of 15,000 

 barrels weekly. 



The crude oil, coming mostly from Pennsylvania, with a specific 

 gravity of 46 to 48 Beaume, is run into horizontal cylindrical stills 

 of wrought-iron, heated by anthracite fires. Eight of these stills have 

 a capacity of 600 barrels each, and there are eight smaller ones. 

 From these stills pipes lead to large worms, cooled by running 

 water, and connected with a series of small tanks, so that the prod- 

 ucts from each still can be separately collected, and the successive 

 portions that come from the still can be kept apart, according to their 

 specific gravity. 



At about 160 Fahr. (70 C.) the gases begin to come off abun- 

 dantly, and these are conducted from the lower end of the worms to 

 heat the steam-boilers. At about 225 Fahr. (107 C.) gasoline, hav- 

 ing a specific gravity of 85 B., begins to run from the worm ; after 

 an hour and a half, at a temperature of 325 Fahr. (163 C.) naphtha 

 begins to run, with a density of 74 B., and continues for about three 

 hours; at 350-400 Fahr. (177-200 C.) benzine, with a density of 

 62 B., begins and runs about one hour. For the remainder of the 

 heat, about thirty hours, illuminating oil is collected, with a density 

 of 48-50 B., and ending with a temperature of 750 Fahr. (398 C). 

 The residuum, having a density of 20 B., is drawn off and shipped in 

 barrels to the paraffine and lubricating oil-works. Steam is then run 

 into the still for nearly two hours to remove the gas, the man-hole is 

 opened, and the coke scraped off to be used for fuel. 



The results of this operation are about as follows : 



Gasoline 3 per cent. 



Naphtha 10 " " 



Benzine 3 " " 



Illuminating oil 75 " " 



Residuum 4 " " 



Coke and loss 5 " " 



Total 100 



The residuum yields by subsequent treatment paraffine to the 

 amount of about one per cent, of the crude petroleum. 



The illuminating oil comes from the worm at a temperature of 



