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

 Table VIII. 







P. 



mr-\-nv. 



~P — (mr+nv). 



Acetaldehyde 



Propionic aldehyde ... 

 Isobutyric aldehyde . . . 



Dimethyl ketone 



Methylpropyl ketone . 



CH3.COH 



C 2 H 5 .COH 



C 3 H 7 .COH 



CH 3 . CO . CH 3 . 



C0 {c%} 



H . COOH . 



124630 

 168930 



212830 



172400 

 261300 



133730 



180890 

 222850 



284340 



251500 

 341200 



165030 

 210120 

 209300 



253680 

 298660 

 265910 

 258530 

 295700 

 216800 



Sr+v 



5r-\-2v 

 7r+Sv 



6r+2v 

 l0r-\-4:V 



r 



3r+v 

 5r+2v 



Qr+2v 



Qr 

 I0r+2v 



4r 



Qr+v 

 Qr-\-v 

 8r-\-2v 



I0r+3v 

 Sr+2v 

 8r+2v 



I0r+3v 

 Qr+2v 



COH = 65430 

 65530 

 65230 



CO = 54000 

 54500 



CO. OH =118730 

 121690 

 119450 



(CO) 2 =165940 



161500 

 162810 



105030 

 105920 

 105100 

 105280 

 106060 

 117510 

 110130 

 103100 

 98400 





CH^.COOH 



C 2 H..COOH . 



0(CO.CH 3 ) 2 ... 



CONCHA 





Acetic anhydride 



Dimethylic carbonate . 

 Diethylic carbonate ... 



Methylic formate 



Methylic acetate 



C0 3 (C 2 H 5 ) 2 



H. COOCH, 



CH 3 .COOCH 3 ... 

 H.COOC 2 H 5 ... 

 H.COOC,H 7 ... 

 C 3 H 7 .COOCH 3 . 

 CH 3 .COOC.,H 5 . 



c 2 h 5 .cooch; . 



H.COOC 4 H 9 ... 

 H.COOC 3 H 5 ... 



Propylic formate 



Methylic isobutyrate. . . 



Methylic propionate.. 

 Isobutylic formate . . 

 Allylic formate 



group O : C . O . C : O. This value, however, is very nearly 

 thrice (165940 = 3.55310) that found for the group CO in 

 ketones and acids, viz. 54250 units ; so that it may be assumed 

 that equal amounts of heat are developed in the formation of 

 the groups C : O and C . O . C, both of which contain an 

 oxygen atom united by two bonds to carbon. The values 

 found for methylic and ethylic carbonate afford confirmation 

 of this conclusion, inasmuch as 162155 units — the mean of 

 the two values 161500 and 162810 units — which is the amount 

 of heat developed in the fixation of the three oxygen atoms 

 in the group O . O . CO . O . C, is thrice 54052. 



It will be observed on reference to the table that the heats 

 of combustion of ethylic acetate and of methylic, isobutylic, 

 and allylic formates give values for P — (mr + nv) very different 

 from those found for the five preceding ethereal salts in the 

 list. Thomsen states that in the first instance the specimens 

 of ethylic acetate examined gave very variable results, and 

 that he had great difficulty in obtaining a pure substance by 

 fractional distillation*. Ultimately two samples were prepared 



* E. SchifF has also recently called attention (Liebig's Annalen, 1886, 

 vol. 234. p. 308) to the great difficulty of obtaining pure ethereal salts. 



