BETWEEN THE VISCOSITY OF LIQUIDS AND THEIR CHEMICAL NATURE. 533 
The observations were reduced by means of Kopp’s values for the density 
d(07i°) = 0'8095, and his expression for the thermal expansion 
V = 1 + -02104139^ + -067836^2 + -0717618^3 
(‘Jahresbericht,’ 1847, 66), 
Taking 
777 = ‘015328 773 = ‘004764 77^ (calculated) = ‘009545 
= 7°‘16 ^3 = 73°‘57 ^3 (from curve) = 38°‘15, 
we obtain the formula 
251908000-0 
~ (209-63 + 0^-3731 ’ 
which gives the following calculated values :— 
t Mean temp. 
i 
V- 
Difference. 
Observed (mean). 
Calculated. 
0 
7-16 
-015328 
-015328 
•000000 
13-23 
■013573 
-013584 
+ -000011 
19-22 
-012094 
-012097 
+ -000003 
25-24 
-010792 
-010798 
+ -000006 
31-89 
-009560 
-009557 
- -000003 
37-51 
-008644 
-008642 
- -000002 
42-84 
-007875 
-007872 
- -000003 
49-37 
-007047 
-007041 
- -000006 
55-57 
-006354 
-006349 
- -000005 
61-07 
-005815 
•005804 
- -000011 
67-55 
-005253 
•005233 
- -000020 
73-57 
-004764 
•004764 
•000000 
Propyl Alcohol. CH 3 .CH 3 .CH 3 OH. 
Received from Dr. Perkin. After standing over anhydrous copper sulphate for 
some time it was distilled. It boiled between 95°‘5 and 96°‘5, r = 51°, t = 29°‘5 
(emergent column). Bar. 755‘9 millims. Corrected and reduced b.p. = 96°‘6, 
Determinations of vapour density :— 
Found, I., 29‘51 ; IL, 29‘44, Calculated, 30-00, 
Observations for viscosity ; 
