PROPERTIES OE MATTER IN THE GASEOUS STATE. 
749 
Table IX.—Thermal transpiration of hydrogen by meerschaum plate No. 3 (-44 inch 
or 11*2 millims. thick). Temperature of steam, 212° F. or 100° C.; temperature 
of water, 63° F. or 17° C., May 15 and 18; temperature of water, 65° F. or 18° C., 
July 10. 
Mean pressure by vacuum 
gauge. 
Difference of pressure by siphon gauge. 
Ratio of mean 
pressure to 
Log of mean 
Log of 
difference of 
pressure. 
May 15. 
May 18. 
July 10. 
difference of 
pressure. 
pressure. 
inches. 
35-00 
millims. 
889-0 
inch. 
inch. 
inch. 
•7940 
millims. 
20-17 
44 
2-544-1 
2-900-3 
34-00 
863-6 
•7930 
20-14 
43 
2-531 
2-899 
32-00 
812-8 
•7930 
20-14 
40 
2-505 
2-899 
30-00 
762-0 
•7670 
19-48 
39 
2-477 
2-885 
29-50 
749-3 
•7760 
19-71 
38 
2-470 
2-889 
. . 
•7776 
19-75 
37 
9 ? 
2-890 
27-50 
698-5 
•7600 
19-30 
36 
2-439 
2-880 
22-00 
558-8 
•6914 
17-56 
32 
2-342 
2-840 
18-50 
469-9 
•6250 
15-87 
29-5 
2-267 
2-795 
18-00 
457’2 
•5710 
14-50 
31 
2-255 
2-757 
55 
•5960 
15-14 
30 
2-255 
2-775 
12-00 
304-8 
•4800 
12-19 
25 
2-070 
2-681 * 
11-40 
289-6 
"4626 
11-75 
24-6 
2-056 
2-664 
10-50 
266-7 
•4156 
10-56 
25 
2-021 
2-618 
7-70 
195-6 
•3594 
9-13 
21 
1-886 
2-555 
7-60 
193-0 
■3160 
8-03 
24 
1-880 
2-500 
6-95 
176-5 
•3046 
7-74 
23 
1-842 
2-484 
4-75 
120-6 
■2206 
5-60 
23 
1-676 
2-343 
55 
•2584 
6'57 
18 
2-412 
4-50 
114-3 
•2120 
5-38 
21 
1-653 
2-326 
3-00 
76-2 
•1568 
3-98 
19 
1-477 
2-200 
55 
55 
■1784 
4-53 
17 
2-251 
2-60 
66-0 
1420 
3-60 
18 
1-414 
2-152 
1-95 
49-6 
•1204 
3-06 
16 
1-290 
2-080 
1-70 
43-2 
•1063 
2-70 
16 
1-230 
2-026 
1-25 
31-8 
•0784 
1-991 
16 
1-096 
1-894 
1-10 
27-95 
■0630 
1-600 
17 
1-041 
1-799 
1-00 
25-40 
•0660 
1-676 
15 
1-000 
1-819 
0-70 
17-78 
•0380 
0-965 
18 
0-845 
1-580 
0-65 
16-51 
•0325 
0-825 
20 
0-813 
1-511 
0-60 
15-26 
•0380 
0-965 
15 
0-778 
1-500 
0-35 
8-88 
•0250 
0-635 
14 
0"544 
1-297 
0-32 
8-13 
•0200 
0-580 
16 
0-505 
1-301 
0T75 
•0150 
0-381 
12 
0-243 
1-176 
Although this plate was so much thicker than meerschaum plate No. 2, the results 
were no greater. They appear rather less, but this was owing to the somewhat higher 
temperature of the water, which would reduce the results in Table IV. in the ratio 
8 to 9, and when this correction is applied the agreement is very close. 
Effect of the thickness of the plate. 
26. It had been expected, however, that the extra thickness ot the plate No. 3 
would have caused it to give somewhat higher results, and its not doing so seemed to 
