88 Prof. H. E. Armstrong on the Determination of 



the combination of the bromine is 5430, 6040, and 6290 units; 

 whereas in the case of allyl bromide, as in that of allyl chloride, 

 there is a somewhat larger amount of heat developed, viz. 

 7120 units. 



A comparison of the heats of combustion would appear to 

 show that isomerism such as obtains between allyl chloride and 

 chloropropylene and between ethylene and ethylidene chlorides 

 has no influence : 



p tt n f Allyl chloride 442500. 



^3*W | Chloropropylene ... 441190. 



nT r n] /"Ethylene chloride ... 272000. 

 o 2 u 4 ui 2 | EthyMene chloride m 272050. 



(10) Heat of Combustion of Alcohols. — The thermal be- 

 haviour of isomeric alcohols of the C n H 2n+1 .OH series is 

 very different from that of isomeric paraffins and their haloid 

 derivatives, as their heats of combustion are by no means the 

 same — the primary having higher heats of combustion than 

 the secondary, and the secondary higher than the tertiary. 

 The heat developed in the formation of the group C . OH may 

 be calculated by deducting from the observed heat of formation 

 at constant volume of the alcohol that of the hydrocarbon 



radical, assigning to r— ~, as before, the value 15000 units, 



and to v l { = v 2 ) the value 14200 units. The numbers thus 

 calculated are given in the last column of Table VI. It will 

 be noticed that nearly the same values are found for the six 

 primary alcohols and (which is remarkable) phenol, and that 

 considerably higher values result in the remaining cases, 

 especially in that of trimethylcarbinol. 



(11) Heat of Combustion of Ethers. — An ether being re- 

 presented by the formula C a H 6 . O . Call^, its heat of formation 

 may be expressed by the equation 



~P=(b + l3)r + nv + <n, 



where n represents the number of single and double bonds, 

 and rj the heat developed in the fixation of an atom of oxygen 

 by two carbon atoms. 



Deducting the heat of formation of methylethyl ether from 

 that of methylallyl ether, the difference will be the value 



of l?2, 



185570-171560=14010=%. 



In like manner, deducting the heat of formation of methyl- 

 ethyl ether from that of methylphenyl ether, 



282490-171560 = 110930 = 8i; ; .\ ^ = 13870. 



