BETWEEN THE VrSCOSITT OF LIQUIDS AND THEIR CHEMICAL NATURE. 529 
Para-xylene (Para-dimethyl benzene). C 6 H 4 ,(CH 3 ) 3 { 1 :4). 
We are indebted to Dr. Moody for a sample of this hydrocarbon. It was prepared 
from Kahlbaum’s “ pure ” para-xylene ; this gave on snlphonation a clean sodium salt, 
which was nearly, if not quite, pure. The sodium salt was re-crystallised twice, and 
then hydrolysed. The regenerated hydrocarbon w^as dried and placed in a freezuig 
mixture. By constant stirring the solid hydrocarbon was obtained in small crystals. 
When about half the liquid had solidified, the crystals were separated by a filter-pump 
and allowed to drain for over an hour at the ordinary temperature ; the crystals were 
then melted and distilled over sodium. 
On redistillation, after standing over sodium wire for several hours, the hydro¬ 
carbon boiled between 138°’37 and I38°’67. Bar. 766‘4 milHms. Corrected and 
reduced b.p. = 138°’23. 
Determination of vapour density :— 
Found, 52'84. Calculated, 53’00. 
An attempt was made to take the first viscosity observation at 0°’35, but although 
the para-xylene was liquid to begin with, it solidified shortly after starting the experi¬ 
ment. The crystals began to soften at about 10°, and were completely melted at 15°. 
After complete liquefaction the temperature was allowed to fall to about 8°, and the 
first observation was then made. 
Left limb. 
Right limb. 
Temp. 
Press. 
Corr. 
V- 
Temp. 
Press. 
Corr. 
n- 
0 
8-31 
104-15 
- 0000.34 
•007513 
0 
8-25 
104-05 
•000034 
•007522 
20-.52 
104-19 
-000040 
•006387 
20-54 
104-12 
•000040 
-006395 
31-20 
104-20 
-000045 
■005611 
31-26 
104 11 
•000045 
-005615 
41-92 
104-21 
•000050 
•004975 
41-78 
104-11 
•000050 
•004989 
53-61 
104-19 
-000055 
•004410 
53-57 
104-10 
•000055 
•004415 
64-82 
104-19 
-000061 
•003958 
64-93 
104-12 
•000061 
•00;i956 
77-38 
104-46 
-000067 
•003532 
77-16 
104-35 
•000067 
•003536 
88-88 
104-58 
•000U73 
•003197 
88-87 
104-52 
•000073 
•003201 
100-81 
104-71 
-000079 
•002903 
10087 
104-62 
■000079 
•002902 
111-76 
104-03 
•000084 
•002665 
111-90 
103-94 
•000084 
-002661 
123-23 
104-15 
■000090 
•00-2447 
123-29 
104-04 
•000090. 
•002448 
135-19 
104-19 
•000096 
•002249 
135-24 
104-11 
•000096 
•002247 
In reducing the observations, Pinette’s expression for the thermal expansion, 
V = 1 -f • 0397013 ^ -f -008714^ -f •085287^3, 
and his value for the relative density, (0°/0°) = 0’8801, have been employed 
(‘ Annalen,’ 243, 51, 1884). 
MDCCCXCiy.—A. 3 Y 
