8 



Dr. S. Young on the Boiling-Pointi. 



(6) When the boiling-point is given in such a form as 

 160° to 161° at 750 mm., the middle temperature, roughly 

 corrected to 760 mm., has been taken. 



A few of the data included in the tables are doubtful ; it 

 seems probable, for example, that the observed boiling-points 

 of rc-propyl ethylene, propylamine, heptamethylene, and 

 methyl ethyl ether are considerably too high, and that those 

 of dioctyl ether, o-methyl ethyl benzene, and probably 

 ^-xylene are too low, while the boiling-points of some of the 

 aldehydes seem doubtful. 



In my presidential address to the Chemical Section of the 

 British Association at Cambridge the only data given were 

 the mean differences between the calculated and observed 

 values of A, and the number of values from which the means, 

 were calculated, each homologous series being, however, 

 dhdded when necessary into two groups. Since the address 

 was printed a few more boiling-points have been found, and 

 a mistake has been discovered in the data for the ethers. 

 The amended data are given in Table IV. 



Table IV. 



Homologous Series. 



Alkyl chlorides , 



,, bromides 



„ iodides , 



Isoparaffins , 



defines H C = CHE 

 HRC^CHE' 



Polyraethvlenes 



Toluene, &c„ C G H 5 R 



Xylene, &c., C 6 H 4 



fCJL 

 1 B* 



Ethyl toluene, &c., C G H 4 [ C & 



Ethers 



Aldehydes 



Amines 



Hydrosulphides 



Total 



Lower Members. 



No. of 

 values 

 of A. 



12 

 2 



2 



9 



31 



Mean cliff. 



between 

 calc. & obs. 



■values. 



+2-75 

 + 1-12 

 +0-52 



+0-45 

 +3-40 



-0-62 



+5-29 

 + 1-98 



+8-22 

 +3-55 



+3-50 



Higher Members. 



No. of 

 values 

 of A. 



49 



Mean diff. 



between 



calc. & obs. 



values. 



o 

 -1-04 

 -1-25 



-LOO 



+0-57 

 -2-35 

 +0-52 

 -3-85 

 4-0-68 



+ 1-38 



-0-05 



4-0-87 

 4- J "30 

 -1-1-68 

 -0-50 



•005 



