102G 
PROFESSOR J. W. MALLET ON A REVISION 
temperature and pressure, and to take advantage of a time when these were not 
undergoing much change. The level of the mercury having been noted on the 
millimetre scale, the corresponding volume was afterwards determined by calibration 
with mercury, weighed in in portions of about half a kilogramme. 
The little piece of apparatus used for the solution of the aluminum is shown in 
fig. 2, in which (a) represents a glass bulb of about 65 m.m. diameter; (6) a tube con¬ 
nected therewith, originally open at both ends, and about 12 m.m. diameter and 
175 m.m. long, but afterwards reduced in length to about 100 m.m. by drawing off and 
sealing, as shown in the figure; (c) is the much smaller tube for carrying off the gas 
produced; (d) is a water jacket like that of the common Liebig’s condenser, formed 
by a piece of larger tube surrounding the ascending limb of (c), and put in place 
before (c) was bent; while ( e , e ) represent small indiarubber tubes for circulating a 
current of water through (d). 
Fig. 2. 
Each experiment was made as follows : The proper quantity of strong solution of 
sodium hydrate, its volume accurately measured, having been introduced into the 
bulb by means of a little tube funnel passed through ( b ), taking care to leave the 
surface of the latter clean, the aluminum (usually in a single piece of elongated shape) 
was passed into (6), held nearly horizontal, so that the metal did not slip down into 
the bulb, but rested 40 or 50 m.m. from it. ( b ) was now drawn off and sealed with a 
well-rounded end. The bulb was touched for a moment or two with the hand, so as 
to expel a very little air, and the outer end of the small tube (c) was introduced into 
the mercury of the trough, taking care that (5) was still kept in such a position as to 
prevent the aluminum coming in contact with the alkaline solution. After a sufficient 
lapse of time for the apparatus to have acquired the temperature of the room, the 
barometer and thermometer and the difference of level of the mercury in the trough 
and in (c) were read off;'* so that, knowing the volume of alkaline solution introduced 
* All readings were of course made from a distance witli the aid of a small telescope. 
