between the viscosity of liquids and their chemical nature. 52 l 
Aromatic Hydrocarbons. 
Benzene. CgHg. 
A sample of carefully purified and thiophen-free benzene which had stood o^ er 
sodium wire for many months, was distilled. It boiled completely between 80°'04 
and 80°‘14. Bar. 757*4 millims. Corrected and reduced b.p. = 80°*2. 
Determination of vapour density ;— 
Found, 38*63. Calculated, 39*00. 
The observations for viscosity gave :— 
Left limb. 
Right limb. 
Temp. 
Press. 
Corr. 
7- 
Temp. 
Press. 
Corr. 
>h 
0 
7-64 
128-12 
•000040 
•007889 
7-71 
128-21 
-000040 
-007881 
7-65 
128-10 
•000040 
•007889 
1.3-44 
128-07 
•000043 
-007169 
13-49 
127-98 
•000043 
•007175 
19-39 
127-84 
-000047 
-006539 
19-39 
127-99 
•000047 
•006550 
26-01 
128-06 
-00005J 
•005943 
25-91 
127-97 
•000051 
•005950 
32-06 
128-10 
-000055 
•005469 
32-09 
128-02 
•000055 
■00.5471 
38-54 
128-37 
-000060 
•00.5013 
38-41 
128-30 
•000060 
•005029 
'45-36 
128-35 
-000065 
•004615 
45-34 
128-24 
•000064 
•004616 
51-69 
128-34 
-000069 
•004284 
51-64 
128-27 
•000069 
•004286 
57-36 
128-.34 
-000073 
•004016 
57-39 
128-26 
•000073 
•004017 
63-29 
128-37 
-000077 
•003766 
63-29 
128-30 
•000077 
•003767 
69-41 
128-28 
-000081 
•003534 
69-41 
128-22 
•000081 
•003537 
75-36 
128-19 
•000085 
•003329 
Observations on the thermal expansion of benzene have been made by Kopp 
(‘Jahr.,’ 1847-48, 66 ) ; Louguinine (‘ Ann. de Chimie et de Phys.,’ 4, 11 , 465, 1867); 
Adrienz (‘ Ber.,*' 1873, 441) ; Pisati and Paterno (‘ Chem. Soc. Trans.’ ( 2 ), 12 , 686 ) ; 
and Lachowicz (‘ Ber.’ 21 , b. 2206). As Kopp’s values approximate very closely to 
the mean of all the other observations, they have been made use of in the reduction. 
His expression for the thermal expansion is 
V = 1 + *02117626^ + * 05127755^2 -h *0880648^1 
We have also employed his value d ( 0 °j 0 °) = 0*89911 for the density. 
By taking 
7 ^^= *0078903 773 = *003329 7^2 (calculated) = *005125 
= 7°*67 ^3 = 75°*36 ^2 (from curve) = 36''^*85, 
MDCCCXCIV.—A. 3 X 
