BETWEEN THE VISCOSITY OF LIQUIDS AND THEIR CHEMICAL NATURE. 509 
In reducing the observations, Zander’s expression (‘Annalen,’ 224, 59, 1884) for 
the thermal expansion, 
V = 1 + •0395794^ -h -069647^2 + •0845729^3, 
was employed : this affords values closely concordant with those given by that of 
Kopp: for the relative density we have adopted the mean of the concordant observa¬ 
tions of Landolt and Zander, viz., cl (0°/0°) = 1’2424. 
Taking 
y)i = ’023851 Vs — ‘005584 77.2 (calculated) = ’011540 
= 7°’59 ^3 = 97°’23 ^2 (from curve) = 43°’07 
we obtain the formula 
32-8143 
“ (59-799 + ’ 
which gives calculated values which agree closely with those obtained by observation. 
Mean temp. 
n- 
Difference. 
Observed (mean). 
Calculated. 
7° 59 
-02385 
•02385 
•00000 
15-9G 
-01951 
•01951 
•00000 
24-16 
-01635 
•01635 
•00000 
32-86 
-01379 ; 
•01381 
-h -00002 
40-36 
-01208 ' 
-01208 
•00000 
48-03 
•01064 
•01064 
•00000 
56-30 
•00937 
•00938 
+ -00001 
64-20 
•00838 
•00837 
- -00001 
72-05 
•00754 
•00754 
•00000 
80-22 
•00681 
•00680 
- -00001 
88-19 
•00619 
•00618 
- -00001 
97-23 
•00558 
•00558 
•00000 
Acetic Acid. OH3.COOH. 
A quantity of “ pure ” glacial acetic acid was cooled below its freezing [)oint, and 
the liquid portion drained from the crystals. These were melted, again frozen, and 
drained as before, the process being repeated four times. The residual portion was 
then melted and placed over anhydrous copper sulphate for several days. The clear 
liquid was decanted and distilled. It boiled at 117°’8. Bar. 754’2 millims. Cor¬ 
rected and reduced b.p. = 118°’l. 
As is well known the vapour density of acetic acid is anomalous. The observations 
