156 



Prof. Sydney Young on the 



XL Ratios of vapour-pressures at corresponding tem- 

 peratures. 

 XII. Ratios of molecular volumes of liquid at corresponding 

 pressures. 



XIII. Ratios of molecular volumes of liquid at corresponding 



temperatures. 



XIV. Ratios of molecular volumes of saturated vapour at 



corresponding pressures. 

 XV. Ratios of molecular volumes of saturated vapour at 



corresponding temperatures. 

 In calculating the molecular volumes the following mole- 

 cular weights have been employed : — 



C 6 H 6 F .... 95-8 

 C 6 H 5 C1 ... 112-2 

 C 6 H 5 Br ... 156-6 



1 C 6 H 5 I ... 203-4 SnCl 4 ....... 2593 



C 6 H 6 ... 77-84 (C 2 H 3 ) 2 ... 73'84 

 CC1 4 ... 153-45 CH 3 OH ... 31-93 



Table I. — Critical Constants. 



C 2 H 3 OH ...45-90 

 C^C-H ...59-87 

 CH3COOH 59-86 



Substance. 



Formula. 



Temperature. 



Pressure, 

 inmillim. 



Volume 



, in c.c. 



Centi- 

 grade. 



Absolute. 



of a gram. 



Molecular. 



Fluorbenzene 



C 6 H 5 F. 



C 6 H 5 C1. 



C 6 H 5 Br. 



C 6 H 5 I. 



C 6 H 6 . 



CC1 4 . 



SnCl 4 . 



(C,H 5 ) 2 0. 



CH.OH. 



C 2 H 5 OH. 



C,H 7 OH. 



CH3COOH. 



286-55 

 (360) 

 (397) 

 (448) 

 288-5 

 283-15 

 318-7 

 194-4 

 2400 

 243-1 

 263-7 

 321 -fi 



559-55 

 (633) 

 (670) 

 (721) 

 561-5 

 556-15 

 591-7 

 467-4 

 513-0 

 516-1 

 536-7 

 594-6 



33912 



(33912) 



(33912) 



(33912) 



36395 



34180 



28080 



27060 



59760 



47850 



38120 



43400 



2-43 



(2-34) 



(1-76) 



(1-47) 



2-82 



2-46 



233 

 (262) 



(275) 



(298) 



219 



147 



Chlorobenzene 



Bromobenzene 



Iodobenzene 





Carbon tetrachloride 

 Stannic Chloride . . . 

 Ether 



Methyl Alcohol 



Ethyl Alcohol 



Propyl Alcohol 













The brackets indicate calculated values. In the case of 

 chlorobenzene, bromobenzene, and iodobenzene the critical 

 temperatures and volumes given depend on the assumption that 

 the critical pressures are equal. The critical constants of chloro- 

 benzene have been observed, but the determinations could not 

 be made with the same degree of accuracy as those of fluor- 

 benzene, and the calculated values have therefore been adopted 

 in this paper. The observed values are: — temperature, 359*2 

 to 359-45 ; pressure, 33926 to 33998 millim. ; molecular 

 volume, 262 to 275 cubic centim. The temperatures given 

 in the original paper (Trans. Chem. Soc. lv. p. 518) are 

 360-55-360-8; but the boiling-point of mercury, the vapour 

 of which was employed as a jacket, has since been shown to 

 be lower than was at that time adopted. 



