482 MESSRS. T. E. THORPE AND J. W. RODGER ON THE RELATIONS 
In reducing the observations we employed the value d (15°/15°) = 1'74343 given by 
Perkin (‘ Chem. Soc. Trans./ 45, 525) for the relative density, and the expression 
V -- 1 + -0395566^ + -0631753^2 + •08500821i3 
for the thermal expansion (Thorpe and L. M. Jones, loc, cit.). 
Taking 
Tyj = '032903 7/3 = '004941 (calculated) = '012750 
= 0°'39 ^3 = 142°'44 ^3 (from curve) = 53°'12, 
we obtain 
79-485 
— (75-fio + ’ 
which gives the following calculated values :— 
Mean temp. 
V- 
Difference. 
Observed (mean). 
Calculated. 
0 
0-39 
-03290 
•03290 
•00000 
13-67 
-02456 
•02463 
+ -00007 
26-94 
-01916 
•01919 
+ -00003 
40-80 
-01528 
•01528 
•00000 
53-18 
-01274 
•01274 
•00000 
66-90 
-01065 
•01062 
- -00003 
80-60 
-00903 
•00900 
- -00003 
93-63 
-00781 
•00779 
- -00002 
107-15 
-00680 
•00679 
- -00001 
121-74 
•00593 
•00591 
- -00002 
133-75 
-00532 
•00532 
•00000 
142-44 
•00494 
•00494 
•00000 
Acetylene Bromide. (Symmetrical Dibromethylene.) (CHBriCHBr.) 
Prepared by Dr. Plimpton, to whom our thanks are due for the specimen. The 
liquid boiled between 108°'9 and 109°-7. Bar, 757'8 millims. Corrected and reduced 
b.p. = 109^-4. 
Vapour density : 
Found, 92'04. Calculated, 92'77. 
Observations for viscosity :— 
