52 
BULLETIN 1036, U. S. DEPARTMENT OF AGRICULTURE. 
tanks and cylinders in an economical manner. The average specific 
heat over a range from 15° to 90° C. has been roughly determined in 
the Forest Products Laboratory. The results given in Table 17 are 
not absolute specific-heat data, but include also the latent heat of 
fusion if the creosote is solid at room temperature. They are, there- 
fore, somewhat greater than true specific-heat values. The SDecific 
heat of nine creosotes are shown in Table 17. 
Table 17. — Specific heat of coal-tar creosotes. 
Creosote 
Specific 
heat. 
Creosote 
Specific 
No. 
No. 
heat. 
614 
0.337 
679 
0.373 
636 
.353 
680 
.349 
638 
.332 
687 
1.443 
641 
.323 
740 
.307 
677 
.339 
* This creosote contained large quantities of naphthalene. It was practically solid at room temperature. 
The figure is high because of latent heat of fusion. 
The specific heat of creosotes may therefore be assumed to range 
between 0.30 and 0.45. If water is added, the mixture has a higher 
specific heat than creosote oil, and the rise in specific heat is in direct 
proportion to the amount of water present. Therefore, if treating 
plants are designed to handle aqueous solutions, ample provision 
will be made for the heating of creosotes. 
SPECIFIC GRAVITY. 
The specific gravity of a material is a physical property that is 
easily measured. Because of this fact, it is used to a large extent 
in industry to determine such factors as the strength of solution or 
the quality of oil. 
The specific gravity of straight distilled coal-tar creosotes may vary 
from 1.01 to 1.08 or more. The usual temperature at which specific- 
gravity determinations are made is 38° C. and referred to water at 
15° C. Practically the same result is obtained if the determination 
is made at 60° C. and referred to water at 60° C. 
It is sometimes convenient to measure the specific gravity at some 
temperature other than the ones shown above. The change in specific 
gravity with change in temperature is 0.00077 per degree centigrade, 
or 0.00043 per degree Fahrenheit. This correction factor may be 
added to the determined value if the tempertaure is above the 
standard, or subtracted if it is below. 
COEFFICIENT OF EXPANSION. 
The factor usually termed the coefficient of expansion is the amount 
of change per unit volume if an oil is heated through 1 degree. 
This factor changes with the temperature and also with the different 
