

Atomic Laws of Thermochemistry. 39 



Along with this we had better take the equations for gaseous 

 H 2 and gaseous H 2 2 , namely, 



(0)+(H) + (H)+/(OH 2 )=59,or/(OH 2 )=59, . (28) 



2(0) + 2(H) + 2/(OH)+/(0'0) = 45, or 2/(OH) -f/(0*0)=45. (29) 

 Now we ought to take/(OH 2 ) = 2/(OH), which would give us 



/(0*0)=-14, (30) 



and /(OH) = 29-5, (31) 



therefore from (27) 



/(O0)=15 (32) 



Thom sen's second result for the alcohols is that the heat of 

 formation of a primary alcohol is less than that of the 

 isomeric secondary and tertiary alcohols ; thus for propyl and 

 isopropyl alcohols the difference is 5*3, for isobutyl alcohol 

 and trimethylcarbinol it is 17*1, and for isoamyl alcohol and 

 dimethylethylcarbinol it is 9*6. These differences are larger 

 than those found by Louguinine (Com.pt. Rend, xci.), namely, 

 2 for propyl and isopropyl alcohols, and 5 for amyl alcohol 

 and dimethylethylcarbinol. Thus the values of the differences 

 in the heats of formation of isomeric alcohols are too irregular 

 to encourage any further study of them at present until a 

 better guarantee of experimental accuracy can be given. 



4. Ethers. — In the simple and mixed oxides, as in the 

 haloid compounds, Thomsen adopts slightly different values 

 for his fundamental constants, namely, w 1 = t? 2 = 13 , 9 instead 

 of 14*2, and r= 15*76 instead of 15, and then, as in the ethers 

 two carbon atoms are joined by an oxygen atom, he finds for 

 the thermal value of such junction 2x 15*76 ; the reason for 

 adopting different values for the fundamental constants is that 

 it gives a greater uniformity amongst the values of this 

 junction derived from the heats of formation of eight ethers 

 in Thomsen's list ; but if the old values for v and r are re- 

 tained the values of the heat of junction of an atom to two 

 C atoms only vary within limits which do not exceed those 

 possible by reason of experimental error. In our symbols this 

 2 x 15*76, which Thomsen treats as the heat of junction of two 

 C atoms by one 0, would be /(OOC), and taking the old 

 values r=/(CH) = 15, /(OC) =/(C : 0) =14*2 we get for 

 /(OOC) the following values :— in dimethyl ether 35, in 

 methylethyl ether 37*7, in diethyl ether 43*2, in methylpro- 

 pargyl ether 37*3, in methylallyl ether 37*8, in diallyl ether 



