28 BULLETIN 898, U. S. DEPARTMENT OF AGRICULTURE. 
TURPENTINE TABLES. 
In the purchase or sale of turpentine in large lots, it is often desir- 
able to determine the net weight of the shipment from the measured. 
gallonage, or vice versa. The weight of a gallon of turpentine varics 
with its temperature and its composition, which is not always the 
same, as shown by the fact that at 60° F. (15.5° C.) the specific 
gravity’ of pure American gum spirits varies between 0.862 and 
0.875. 
1 The term specific gravity as applied to liquids and solids is usually defined as the ratio between the 
weights, or more correctly the masses (i. e., the weights in vacuum), of equal volumes of the material under 
discussion and of water, tlie temperature of cach being either definitely stated or implied. 
Tue apparent weight of a body in air is in most cases slightly less than its mass, or weigiit in vacuum, 
due to the buoyant efect of the air displaced by that body. The difference between the weight in air 
and the weight in vacuum is equal to the weight of a volume of air equivalent to the difference between the 
volume of the body being weighed and of the weights used to counterbalance it. All scales are calibrated 
or checked against weights whose weignt has been determined by counterbalancing against standard 
brass weights. 
The statement “specific gravity of turpentine at 60°/60° F. equals 0.864,”’ therefore, means that the mass 
(weight) of any volume of the turpentine at a temperature of 60° I’, is only 864/1000 of the mass (weight) 
of an equal volume of water at the same temperature. ‘Specific gravity, 20°/15,5° C.=6.870”’ means that 
the mass (weight) of any volume of the liquid at a temperature of 20° C. is §70/1000 of the mass (weight) 
of an equal volume of water at 15.5° C. When only one temperature is given, as in the statement “sp. gr. 
~ 15.5° C. =0.864,”’ it is implied or understood that both the liquid and the water are at the same temperature 
as in the first case. 
Whenever the mass of any volume of liquid is compared with the mass of an equal volume of water at a 
temperature of 4° C.,at which temperature the weight of any volume of water is at its maximum, this 
ratio is called the “density’’ of the liquid. Since the density of water is taken as 1.000 at 4° C.,i.e., the 
mass (weight) of 1 cubic centimeter of water at this temperature is 1.000 gram,the statement ‘density, 
15.5° U.=0.870” means that the mass of 1 cubic centimeter of the liquid is 0.870 gram at the stated tem- 
perature, 15.5° C, 
