PROPERTIES OF GASOLINE 27 



The oil manufacturer and dealer, however, know it as 62 to 

 68 GASOLINE, and they know the lighter gasoline as 86 to 

 88 GASOLINE. This speaking of gasoline as being such or 

 such a degree gasoline refers to the grading of it by means of a 

 little instrument called a BAUME HYDROMETER (Bo-ma). 



31. Baume's Hydrometer. This instrument (Fig. 14) con- 

 sists of a glass tube 8 or 10 in. in length. Near its lower end this 

 tube has been blown into a large bulb, and still farther 

 down, at its very end, it has been blown into a small 

 bulb and sealed. Some mercury or small shot is 

 dropped down the tube into the lower, small bulb. 

 Some melted sealing wax is then dropped down inside 

 the tube and made to close the opening between the 

 two bulbs. Care is taken to have the instrument 

 so weighted that it floats with the stem above the 

 large bulb above the surface when placed in water. 

 The instrument is then GRADUATED by floating it in 

 lighter liquids and marking the scale on a strip of 

 paper which is slipped down inside the stem. The 

 stem is then sealed and the instrument is complete. 



The instrument is called a Baume hydrometer 

 (hydro water, and metron measure) , because Baume* 

 invented the scale used upon it. Oils of all kinds 

 including the products of petroleum, also syrups, FIQ " 14 

 vinegars, and many other liquids are regularly bought BaumS 

 and sold on the market at prices which vary according 

 to the density of the liquids as determined by this 

 hydrometer. It must be remembered that the light gasoline 

 has a lower boiling point and is a lighter liquid per gallon than 

 the heavy gasoline. But it must also be remembered that the 

 grading of the lighter oil by the Baume hydrometer is 86 or 

 88, while the heavy oil grades 62 to 68. That is, it is al- 

 ways true that the lighter the oil, the higher it will grade in 

 Baume* degrees; the heavier the oil, the lower it will grade in 

 Baume" degrees. Kerosene grades about 45 Baume*, and 

 is written "45B." 



