from Water and other Liquids, Sc. 567 
inconvenient lengths. Being destrous however 
to determine the force of the ethereal vapour 
experimentally up as high as 212°, I contrived 
to effect it as follows:—Took a syphon tube such 
as described above, only not quite so long, and 
filled it in the manner above mentioned, with 
ether and mercury, leaving about ten inches.at 
the top of the tube vacant; then having gradu- 
ated that part into equal portions of capacity, and 
dried it from ether, I drew out the end of the tube 
to acapillary bore, cooled it again so as to suffer 
the internal atmospheric air tobe of the proper 
density, and suddenly sealed the tube hermeti- 
cally, thus inclosing air of a known force in the 
graduated portion of the tube, Then, putting 
that part of the tube containing ether into 
boiling water, vapour was formed which forced 
the mercurial column upwards and condensed 
the confined air, till at length an equilibrium 
took place. In this way I found 8. 25 parts of 
atmospheric air of the force 29. 5 were con- 
densed into 2. 00, at the same time a perpendi- 
cular column of 16 inches of mercury in addition 
pressed upon the vapour... Now the force of 
elastic fluids being inversely as the space, we 
have 2. 00 : 29. 5 :: 8. 25 : 121. 67 inches = 
the force of the air within; to which adding 16 
inches, we obtain 137. 67 = the whole force 
VOL. Vv. It 
