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



It therefore appears that v 1 and v 2 have practically the 

 same values in ethers as in hydrocarbons and alcohols. If. 

 now, from the heat of formation, P, of an ether, the value nv 

 be deducted, the difference will be the heat developed in the 

 combination of 5-1- /3 hydrogen atoms and of the two oxygen 

 atoms to the carbon atom. On reference to Table VII. it 

 will be seen that the quotient of P— nv by b 4-/8+ 2 is prac- 

 tically a constant, the mean value being 15757 units, which is 



very nearly the value of ——r*; hence Thomsen concludes 



L 



that the amount of heat developed in combination of an atom 

 of oxygen with two carbon atoms is about the same as is 

 developed by combination of a hydrogen molecule with a 

 carbon atom. 



Table VII. 





O a H B .O.O a H0. 



P— nv. 



b+fi. 



P— nv 

 &+|3+2" 



Dimethyl ether 



CH3.O.CH3 ... 

 CH 3 .O.C 2 H 5 .. 

 C 2 H 5 .O.C 2 H 5 ... 

 CH 3 .O.C 3 H 3 ... 

 CH 3 .O.C 3 H 5 ... 

 C s H 5 .O.0 8 H s ... 

 CH 3 . . C 6 H 5 . . 

 ™ 2 )o 



n = 124950 



1 157690 



2 193210 



1 127290 



2 157790 

 4 184650 

 9 157660 

 1 80110 



6 

 8 



10 

 6 

 8 



10 

 8 

 4 



15619 

 15769 

 16101 

 15911 

 15779 

 15388 

 15766 

 13352 



Me thy lethyl ether 



Diethyl ether 



Methylpropargyl ether... 

 Methylallyl ether 



Diallyl ether 



Methylphenyl ether 



Ethylene oxide \ 



CH 2 J 



In this section occurs one of the most noteworthy of 

 Thomsen's conclusions, viz. that ethylene oxide is in reality a 

 dimethylene oxide of the formula CH 2 . O . CH 2 . The heat of 

 formation of a compound of this formula is 



(4 + 2) 15757 = 94540 units, 



which agrees well with the observed value 93980 units; 

 whereas, assuming the formula to be that ordinarily accepted, 

 the heat of formation should be greater by v, or about 

 14,000 units. 



* It is not quite evident why the value of 77 is calculated in this 

 manner ; if deduced from the equation 



r) — (<p - nv) - (a + B)r, 



giving 2r the usual value (30000 units), its value is considerably higher, 

 viz. 2 . 17475 units in the case of dimethyl ether, for example, which is 

 much above the value of 2r found in previous cases. 



