528 Mr. D. Tyrer on Relations between the Physical 



Indeed, by the aid of the equation LM=K\/v, the latent 

 heat of a liquid (other than those excepted above) can be 

 calculated merely from a knowledge of its formula with a 

 very fair degree of accuracy. In the above table the values 

 of the molecular volume for several liquids marked with an 

 asterisk are calculated from Kopp's atomic volumes, and 

 it will be noticed that in these cases there is a very fair 

 agreement between the calculated and observed latent heats. 



A Relation between the Molecular Volume and 

 the Boiling-Point. 



If the relation LM = K v^Y be combined with Trouton's 

 equation LM = 20*5T we get a very simple equation 



T=K 1 y^V; 



where T is the temperature of boiling, Y is the molecular 

 volume at the boiling-point, and Kj is. a constant. 



The value of the constant in Trouton's equation varies 

 for normal liquids from about 19*5 to 22*5. Taking the 



constant in the equation LM = K y/Y as equal to 1583 we 

 should expect that the value of K x will vary roughly between 

 70 and 80, and will have a very small value for the aliphatic 

 hydrocarbons and ethers. 



The validity of the equation is tested in the following- 

 Table. The values of T and V are the mean results of Kopp, 

 Pierre, Buff, Thorpe, Zander, Gartenmeister, Young, and 

 others. 



Liquid. 



Temperature 



of Boiling T BP 



(absolute). 



Molecular 

 Volume Y at 

 Boiling-Point. 



T 



■"M — 3/-' 



Aliphatic Esters. 

 Ethyl formate 



327-3 



330-1 



3539 



350-1 



352-7 



372 



370-9 



374-5 



372 



375-7 



403-4 



396-7 



393 



399-3 



420-6 



84-7 

 83-7 

 1070 

 106-0 

 104-6 

 130-7 

 . 129-9 

 128-4. 

 127-8 

 1267 

 150-5 

 1510 

 150-4 

 149-1 

 173-8 



74-53 



75-47 



74-54 



73-98 



74-95 



73-2 



73-2 



74-2 



73-8 



74-8 



75-8 



74-5 



73-9 



75-5 



75-4 



Methyl acetate 



Propyl formate 



Ethyl acetate 



Methyl propionate 



Butyl formate 



Isobutyl formate 



Propyl acetate 



Ethyl propionate 



Methyl buty rate 



n . Amyl formate 



Isoamyl formate 



Ethyl butyrate 



Methyl valerate 







