46 BULLETIN 102, VOL. 1, UNITED STATES NATIONAL MUSEUM. 



sene, fuel oil, and lubricating oil — together with by-products, the 

 process separating the crude oil into its natural components with the 

 minimum of chemical change. The "straight-run" refinery lacks 

 flexibility, because it has no power of producing, for example, 

 more gasoline than the crude oil naturally contains.^ Such plants 

 are situated in the East and other parts of the country where the 

 demand, especially for lubricants, justifies the expense of the practice. 



The third type of refinery is of recent birth, but has made rapid 

 strides toward a great future ; it employs the so-called " cracking " 

 process, which yields, like the "straight-run" plant, a full set of 

 products, but a greater percentage of gasoline than the crude oil gives 

 upon ordinary distillation. This is accomplished at the expense of 

 the heavier component oils, whose molecules are broken or " cracked " 

 into lighter molecules, which constitute just so much additional gaso- 

 line. It is obvious that cracking has developed in response to 

 a growing demand for gasoline; its significance is apparent in the 

 fact that it permits the production of a more valuable product from 

 one less valuable. With an increasing call for gasoline and a de- 

 creasing supply of petroleum, cracking may be called the hope of the 

 future as regards refinerj' advance. 



If we pause for a moment to contemplate the consumption of 

 petroleum in the crude condition, and then the three types of refin- 

 ing — skimming, straight-run, and cracking — it becomes evident that 

 each treatment represents a step in advance over the preceding, and 

 that, while all four prevail to-day, the cracking refinery is in line 

 with true progress and will eventually dominate the situation. 



Eefineries, whatever the type, employ the principle of distillation 

 in their operations. The petroleum is heated in stills and the prod- 

 ucts vaporize, pass off, and are condensed in fractions, representing 

 roughly the materials in demand. These products are then purified 

 by chemical treatment or transformed by chemical means into a 

 series of secondary products. The production of the various kinds 

 of lubricating oils needed for diverse uses represents an intricate, 

 yet single, part of petroleum refining ; and is merely one aspect of the 

 many ramifications found in refinery technique. The refining of 

 petroleum makes heavy drafts upon other .chemical industries — for 

 example, in normal times, about one-tenth of the sulphuric acid pro- 

 duced in the United States goes into petroleum refining — ^but the 

 refinery in turn contributes many essential products to other chemical 

 manufacturing activities. These industrial interrelationships, oft- 

 times overlooked, are of the utmost significance — a fact strikingly 



* Such statements are true In a broad way only ; the reader will understand that 

 rigorous scientific accuracy of statement must be partly sacrificed to gain simpleness of 

 expression. 



