This section is from the book "A Practical Treatise On Friction, Lubrication, Fats And Oils", by Emil F. Dieterichs. Also available from Amazon: A practical treatise on friction, lubrication, fats and oils.

Weight is the measure of gravity. The specific gravity of any body is the proportion which the weight of a certain amount of that body bears to the same amount of another body which is taken as standard. The standard adopted for solid and liquid bodies is water, at the temperature of 60° F.

The specific gravity of liquids is most accurately ascertained by means of the specific gravity bottle, which is so constructed as to hold exactly 1000 grains of distilled water. The water being emptied out and the bottle filled with the liquid to be tested, is weighed on a correct scale. The result gives the weight of a volume of the fluid equal in bulk to 1000 grains of water, and this weight, divided by 1000, represents the specific gravity of the liquid.

The specific gravity of oils and fats, which are all lighter than water, except some of the tar oils, is handily ascertained by means of the Baume Hydrometer, constructed for the weighing of liquids lighter than water. The oil is put in the hydrometer jar - a tall glass vessel - and the hydrometer placed in it so that it will float upright. The specific gravity of the oil is exactly indicated by the degree on the scale of the hydrometer to which the latter sinks. The measure is always taken at 60° F., and for every ten degrees above that temperature, one degree is subtracted from the reading, and for every ten degrees below 60° F., one degree is added to the reading on the hydrometer scale. Fats and oils, solid at ordinary temperature, should be heated until liquid enough to allow the hydrometer to float easily in them, to indicate their specific gravity.

Table of Baume degrees, the specific gravity they represent and the corresponding weight of the liquids per gallon:

Degree Baume. | Specific Gravity. | Pounds in One Gallon |

10 | 1.000 | 8.33 |

11 | .9929 | 8.27 |

12 | .9859 | 8.21 |

13 | .9790 | 8.16 |

14 | .9722 | 8.10 |

15 (castor oil) .9655 | 8.04 | |

16 | .9589 | 7.99 |

17 | .9523 | 7.93 |

18 | .9459 | 7.88 |

19 | .9395 | 7.83 |

20 | .9333 | 7.78 |

21 | .9271 | 7.72 |

22 | .9210 | 7.67 |

23 | .9150 | 7.62 |

24 | .9090 | 7.57 |

25 | .9032 | 7.53 |

26 | .8974 | 7.48 |

27 | .8917 | 7.43 |

28 | .8860 | 7.38 |

29 | .8805 | 7.34 |

30 | .8750 | 7.29 |

31 | .8695 | 7.24 |

32 | .8641 | 7.20 |

33 | .8588 | 7.15 |

34 | .8536 | 7.11 |

35 | .8484 | 7.07 |

36 | .8433 | 7.03 |

37 | .8383 | 6.98 |

38 | .8333 | 6.94 |

39 | .8284 | 6.90 |

40 | .8235 | 6.86 |

41 | .8187 | 6.82 |

42 | .8139 | 6.78 |

43 | .8092 | 6.74 |

44 | .8045 | 6.70 |

45 | .8000 | 6.66 |

46 | .7954 | 6.63 |

47 | .7909 | 6.59 |

48 | .7865 | 6.55 |

49 | .7821 | 6.52 |

50 | .7777 | 6.48 |

51 | .7734 | 6.44 |

52 | .7692 | 6.41. |

53 | .7650 | 6.37 |

54 | .7608 | 6.34 |

55 | .7567 | 6.30 |

56 | .7526 | 6.27 |

57 | .7486 | 6.24 |

58 | .7446 | 6.20 |

59 | .7407 | 6.17 |

60 | .7368 | 6.14 |

61 | .7329 | 6.11 |

62 | .7290 | 6.07 |

63 | .7253 | 6.04 |

64 | .7216 | 6.01 |

65 | .7179 | 5.98 |

66 | .7142 | 5.95 |

67 | .7106 | 5.92 |

68 | .7070 | 5.89 |

69 | .7035 | 5.86 |

70 | .7000 | 5.83 |

75 | .6829 | 5.69 |

80 | .6666 | 5.55 |

85 | .6511 | 5.42 |

90 | .6363 | 5.30 |

95 | .6222 | 5.18 |

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