465 



The author compares the boiling-points thus calculated for five 

 alcohols, C n H m O 4 ; for six acids, C n H m O 4 ; and for sixteen compound 

 ethers, C w H m O 4 , with the results of observation. In almost all cases 

 the concordance is sufficient. 



The author demonstrates in the next place that in many series of 

 compounds other than those hitherto considered, the elementary 

 difference, #C 2 H 2 , likewise involves a difference of x x 1 9 in the boil- 

 ing-point. He further shows that on comparing the boiling-points 

 of the corresponding terms in the several series of homologous sub- 

 stances hitherto considered, many other constant differences in boiling- 

 point are found to correspond to certain differences in composition. 

 Thus a monobasic acid is found to boil 44 higher than its ethyl 

 compound, and 63 higher than its methyl compound ; and this con- 

 stant relation holds good even for acids other than those previously 

 examined, e. g. for the substitution-products of acetic acid. Also in 

 substances which are not acids, the substitution of C 4 H 5 or C 2 H 3 

 for H, occasionally involves a depression of the boiling-points re- 

 spectively of 44 and 63 ; the relation, however, is by no means 

 generally observed. 



The author, in addition to the examples previously quoted, shows 

 that compounds containing benzoyl (C U H 5 O 2 ) and benzyl (C 14 H 7 ) 

 boil 78 (=4 X 14'5-f 4 X 5) higher than the corresponding terms 

 containing valeryl (C 10 H 9 O 2 ) and amyl (C 10 H n ), a relation, however, 

 which is likewise not generally met with. He discusses, moreover, 

 other coincidences and differences of boiling-points of compounds 

 differing in a like manner in composition. Not in all homologous 

 series does the elementary difference #C 2 H 2 involve a difference of 

 x x 19 in boiling-point. The author shows that this difference is 

 greater for the hydrocarbons, CH W _6 and C n H+ 2 ; for the acetones 

 and aldehydes, CH n O 2 ; for the so-called simple and mixed ethers, 

 C w H n+2 O 2 ; for the chlorides, bromides, and iodides of the alcohol 

 radicals, CnH n ^ i, and for several other groups ; that it is, on the con- 

 trary, smaller for the anhydrides of monobasic acids, C n H n _ 2 O6 ; for 

 the ethers, CH w _ 2 Os (which may be formed either by the action of 

 one molecule of a dibasic acid, CH n _ 2 O 8 , upon two molecules of a 

 monatomic alcohol, C n H+ 2 O 2 , or by the action of two molecules of 

 a monobasic acid, C n H n O 4 , upon one molecule of a diatomic alcohol, 

 C M H W+2 O 4 ), and several other series. 



2K2 



