The Bulletin. 9 



hydrogen, and are closely related chemically, though their physical 

 properties are different. They may be divided roughly into two 

 classes. The simplest of these compounds are gases like marsh gas, 

 the ''fire damp" of coal mines. When mixed with air in proper 

 proportions these gases are dangerous explosives. The second group 

 contains liquids of different degrees of volatility and gravity from 

 the light benzine or petroleum ether to the heavy lubricating oils. 

 Kerosene falls in the middle portion of this group. The third group 

 contains solids and is the source of our vaseline and paraffin wax. 



All these different substances are found intimately blended by 

 nature in the homogeneous-looking crude petroleum. The method of 

 separating the crude material into these various usefid products is 

 essentially a process of fractional distillation. When crude petroleum 

 is heated in a distilling apparatus the explosive gases are driven 

 out first. As the temperature rises the volatile liquids, like petroleum 

 ether and benzine, come off. Eoughly speaking, this portion distils 

 between 40° C. and 150° C. On further increase in the heat, the 

 portion known as kerosene distils. A good kerosene should distil 

 between 150° C. and 300° C. This portion is used on a large scale 

 for lighting and cooking. That part of the crude petroleum which 

 remains in the still above 300° C. contains the heavy oils and 

 vaseline. 



Kerosene is usually a colorless or yellowish liquid, often having 

 a decided blue fluorescence. It imparts its characteristic taste to 

 water, although it is practically insoluble in that liquid. It is only 

 slightly soluble in alcohol, but mixes in all proportions with ether, 

 chloroform, benzine, gasoline, and fixed oils, except castor oil. It ■ 

 is a good solvent for many organic substances, and will also dissolve 

 phosphorus, sulphur, and iodine. The specific gravity of ordinary 

 American kerosene is about 0.790 to 0.80 (47 degrees to 45 degrees 

 Baume). 



TESTING OF KEROSENE OIL. 



For contract purposes, the color, odor, specific gravity and flash- 

 ing point are the characters usually to be determined. The burning 

 point or fire test is sometimes taken instead of the flash test; but 

 this is not to be recommended. Of these, the flash test is the one 

 most generally recognized in legal enactments for securing safety. 

 For special purposes, it is often necessary to examine kerosene as 

 to its composition as ascertained by fractional distillation, its il- 

 luminating power as determined by photometric tests, its freedom 

 from sulphur compounds, its acidity or alkalinity and the amount 

 of ash or mineral matter which it will leave on complete com- 

 bustion. 



Good kerosene should be water-white or light yellow, with or with- 

 out blue fluorescence. A decided yellow color often indicates im- 



