300 
MEASUREMENT OF HIGH TEMPERATURES. [fttfci 54 
Table 108. — Transpiration in platinum tubes. Hydrogen. 
[Capillary tribe ISTo. 8. £=40.5 cm . i?=0.0182 cm . "F=565.7 CC . 0=7.8°. p=74.95°"\J 
p 
P-jp 
t" 
— X t" 
p 
6" 
T 
v" 
1+W/R" 
112. 56 
37.59 
107 
10060 
o 
7.8 
22.6 
0. 0001354 
112. 52 
37.55 
107 
10050 
7.8 
22.7 
1355 
112.06 
37.09 
108 
9990 
7.8 
22.8 
1347 
85.75 
10.78 
352 
8160 
7.8 
22.9 
1100 
85.72 
10.75 
354 
8160 
7.8 
23.1 
1101 
85.64 
10. 67 
355 
8120 
7.8 
23.2 
1096 
112.72 
37.75 
107 
10110 
7.8 
23.3 
1365 
112. 67 
37.70 
107 
10090 
7.8 
23.4 
1365 
[Same apparatus with air.] 
120. 47 
45.55 
202 
24000 
7.8 
23.4 
0. 0003240 
120. 55 
45.63 
201 
23930 
7.8 
23.5 
3235 
86.66 
11.74 
676 
17120 
7.8 
23.2 
2311 
86.59 
11.67 
675 
16980 
7.8 
23.0 
2292 
120. 52 
45.60 
202 
24030 
7.8 
22.8 
3238 
The results are very instructive. In the experiments (Fig. 54, p. 304 
tan cp increases with the rate of flow, or, ceteris paribus, with the vis 
cosity of the gas. Hence one would infer that in the case of hydrogen 
and air passing through the same tube, ceteris paribus, the obliquity 
would be decidedly greater. The experiment shows precisely the re 
verse result ; tan cp diminishes more than proportionally to the viscosity 
the ratio (Table 104) being as 3 : 2. 
General remarks. — I regret that my research must be closed withj 
these experiments, and that it is not expedient to continue the work] 
further. To do this I should need to repeat the work with special care] 
in the measurement of temperature and in the determination of the ca- 
pillary radius. Nevertheless, the survey of the present field of inquiry ^ 
is by no means unsatisfactory. My results show conclusively that the ■ 
character of the internal surface of the transpiration tube is of marked] 
influence on the result. The absence of obliquity (cp) in glass, and its] 
frequent occurrence in metallic tubes, may be referred to the smooth- 
ness and roughness of the respective internal surfaces. Bough surfaces 
are associated with eddies aloug the line of flow, by which it is retarded 
and apparent viscosity is increased. The absolute value of viscosity 
measured by transpiration through metallic tubes is greater than the 
viscosity measured by transpiration through glass tubes. This I have 
in general found, and although the effect of the discrepancy, possibly 
due to roughness, is not vital in case of my smallest tube, No. 10 (Tables 
81 to 90, R = 0.008 cm ), I have none the less thought it wise to state my 
result, ?/'=tjo (1+tf Q")* , with caution, and to pursue the present critical 
(954) 
