52 



BULLETIN 1036, V. S. DEPARTMENT OF AGRICULTURE. 



tanks and cylinders in an economical manner. The average specific 

 heat over a range from 15° to 90° G. 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 soecific 

 heat of nine creosotes are shown in Table 17. 



Table 17. — Specific heat of coal-tar creosotes. 



Creosote 



Specific 



Creosote 



Specifie 



No. 



heat. 



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 centigi-ade, 

 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 oii is heated through 1 degree. 

 This factor changes with the temperature and also with the different 



