90 
DR. T. E. THORPE AND MR. J. W. RODGER ON THE RELATIONS 
Mean. temp. 
'/• 
Difference. 
Observed fmean). 
Calculated. 
0°-44 
•002783 
-002783 
000000 
5-15 
-002647 
•002649 
-•000002 
10-8,3 
-002.502 
•002499 
+-000003 
15-33 
-002388 
•002389 
-•000001 
20-25 
-002279 
•002276 
+-000003 
25-15 
-002172 
•002172 
000000 
The above coefficients are, on the average, only about 1‘5 per cent, smaller than 
those found for normal pentane, whereas the numbers given by the original sample of 
iso[)entane were about 4 per cent, smaller. 
On substituting the above for the original values, the relationships previously 
traced between the viscosity magnitudes of the paraffins are slightly altered. Since, 
however, all the lower paraffins we examined were prepared from petroleum, we do 
not at present propose to make the substitution, as the values already given probably 
express the relative etfect of chemical nature more correctly than would be the case 
if the hydrocarbons were prepared partly by other methods. As regards the absolute 
value of the viscosity coefficients, thei’e can be little doubt that the numbers afforded 
by the isopentane from amyl alcohol are to be jareferred. 
Ethyl Benzene. CgHg.CHg.CHg. 
The specimen of ethyl benzene previously examined was prepared by fractionating 
a sample obtained from Kahlbaum, whereas its tlu’ee isomers, the xylenes, were 
jirepared for us by Dr. G. T. Moody from the pure sodium salts of the corresponding 
SLilphonic acids. As Dr. Moody kindly placed at our disposal a quantity of ethyl 
benzene, also prejiared from the sodium salt of its sulphonic acid, a substance 
crystallizing in beautiful [dates and having the formula CgH.j.C,,H 5 .SOgNa d- ^HgO, 
we carried out a fresh series of viscosity observations. 
On distilling from sodium wire, the boiling-point varied between 136°'05 and 
13G°'10. Bar., 764'3 millims. Corrected and reduced b.p. 135°'86. 
The value given by the original sample was 135°'92, 
fhe following are the viscosity observations :— 
