412 
MESSRS, T. E. THORPE AHD J. W. RODGER ON THE RELATIOXS 
by a cord, and pulley arrangement as shown in the figure. The length of the coixl, 
which varies with the atmospheric conditions, is adjusted, by a hook and chain. Two 
sets of stirrers fixed to the rods at different heights move in front of and behind 
the glischrometer in the inner compartment, and of course at the sides in the outer 
compartment. 
Lids pierced with holes for the stirring rods, thermometer T, and india-rubber tubes 
E, E', cover in the top of the bath. The lids covering the outer compartment can he 
removed or replaced, even while the stirrers are in motion, without disturbing anything. 
The rubber tube E connects the right limb of the glischrometer with the glass 
tube 0, in which is inserted the three-way cock Z. In the same way E' connects 
the left limb of the glischrometer with the tube 0' fitted with the three-way cock Z'. 
At P, 0 and 0' are united by a T-piece which leads to the bottle M containing a 
cpiantity of sulphuric acid, vdiich can be abstracted or replaced by means of the 
siphon W. The acid serves to dry air in its passage from the reservoir L to the 
glischrometer. When hygroscopic liquids are being experimented upon, the exit 
tubes of the three-way cocks are provided with small tubes filled with calcium 
chloride to prevent access of atmosplmric moisture to the glischrometer. In this way 
it is insured that dry air only is in contact with the liquid under examination. 
By means of the tube N, which extends from within a few millimeters of the 
surface of the acid in M to a centimeter or so below the cork L', and which is fitted 
with the cock Q, the air in M may be put into communication with the large air 
reservoir L. This consists of a glass bottle of about 30 litres capacity, encased in a 
wooden box, and surrounded with sawdust to prevent excessive fluctuation of tempe¬ 
rature. A glass tube A', which reaches to within 5 millims. of the bottom of L, is 
connected, as shown, by india-rubber tubing with the water reservoir B. The air in 
L is compressed by raising the water reservoir, the height of which can be regulated 
l)y a cord leading by a system of pulleys to the stud X, in close proximity to the 
position occupied by the observer, and to the water manometer D, D, wLich indicates 
the pressure set up in the confined air-space. The manometer is connected with the 
air reservoir by the tube I, I, which has a common termination wdth the tube N. 
Leading from L to the air is the tube IT furnished with a stop-cock. This tube is 
but seldom used ; it serves to make fine adjustments of the pressure by allowing 
small quantities of air to escape from L, and it is also useful when it is necessary to 
quickly bring the air in L to atmospheric pressure. The three-way cocks Z and 2! 
serve to put either limb of the glischrometer in connection with the atmosphere or 
with the air reservoir, or to cut ofi' communication of either limb with the reservoir 
or the atmospliere. By their means the air reservoir may also be put into connection 
with the atmosphere. 
When the apparatus is not in use, and the glischrometer has been removed from 
the bath, the cocks Z and 71 are turned so as to cut off communication from L to the 
air, and the reservoir R is hung upon a peg which is attached to the table at a level 
