Rk. H. Richards—Jet Aspirator for Laboratories. 423 
From which we may obtain the following table: 
Taste IV. 
Actual ratio. Ratio of Difference between 
Air tension: Water pressure. w? : a? pressure and area ratios, 
1°95 < 
1°961 1°5 + 461 
2°170 2° + ‘170 
3°120 3° + ‘120 
3°220 4° — °*780 
3°793 5° —1°207 
13°148 15° — 1°852 
This table shows a distinct variation from the theory enun- 
ciated above, QXa?=P: w?, and so long as the actual pressure 
ratio is larger than the theoretical area ratio, it would seem to 
be accounted for by friction; but when, as in the last three 
cases, it becomes less, I confess I am at a loss to discover the law. 
The differences form a very nice series, growing less and less 
until they become negative quantities, but up to the time of 
writing I have failed to ascertain the cause. At the first glance 
it looks as if the water was doing more than its theoretical 
amount of work ; momentum surely cannot account for it. 
Experiments to determine the relative amounts of air and 
water used by the different aspirators under a constant air ten- 
sion, and in each case with that water pressure which is the 
minimum required to produce its best vacuum. Barometer 
767, air 74° F., water 78° F. 
Record of experiments. 
Aspirator.G,. Gp. H. h. H—hA. Time. Amt. air. Amt. water. 
No.1 17384 906 450 374 76 Imin. 512cc 1837c.c. 
rae “ 
No 1000 450 374 76 « 
NG. a. = © 910 «450. -874: 96. © 578 1227 
No.4 « 570 470 350120 * 900 1644 
No5 « 550 460 362 98 * 634 1016 
No.6 « 471 450 -374 76 “ 157 1110 
nay. 8 900 600 186414 “* 332 2266 
|e ee ee. “ «“ 182 1840 
No. 3 c 910 “ “ “ “ 225 1469 
No. 4 6c 570 “ “ “ “ 383 1754 
mo. 5 s 550—Cts “ « & 470 1108 
No. 6*1755 476 “ “  « «“ 520 1160 
Calculated’ statement for comparison of relative air and water 
volumes of the different aspirators. 
* Tried at another time; bar. 764, air 77°, water 72°. 
