( 951 ) 
Wire was wound on it while it was still hot, the ends of the platinum 
wire were fused into the glass and then each of them was welded 
in the blowpipe to two platinum leads. 
In the present instance the cryostat vessel was a transparent double- 
walled vacuum glass. In order to keep the lowest temperature always 
in the bottom of the cryostat by diminishing the evaporation it was 
surrounded by a second transparent vacuum glass containing liquid 
air; the latter was protected from precipitation of mist on its outer 
surface by another glass filled with alcohol whose temperature was 
kept above the temperature of the room. (Cf. e.g. Comm. N°. 108). 
When the equilibrium that was wanted for a measurement has 
been reached and the temperature measured while the equilibrium 
has been maintained, the tap /:, is closed, the volumenometer and 
the dead space evacuated (keeping /, elosed)-and then the gas is 
removed from the dilatometer to the volumenometer. 
The temperature of the volumenometer is kept constant by a 
stream of water delivered by the thermostat described in Comm. N°. 70. 
Thermometers of the requisite accuracy for each measurement were 
placed at 64 in the bath and also at 9... where they were bound 
to the tubes etc. and were as far as possible wrapped along with 
them in one common layer of wool. 
The volumenometer, the manometer tube with scale alongside and 
the two limbs of the barometer Bar are so disposed around a three 
telescope cathetometer (Comm. N°. 60) that they can all three be 
read in succession by simply turning the cathetometer round its axis. 
To facilitate adjustment the barometer and the scale are placed on 
small tables (Comm. N°. 95¢) which allow of horizontal motion by 
screw travels, and which can undergo alteration with respect to the 
vertical. Electric lamps serve to illuminate small vertically movable 
screens with slits placed behind the menisci, or, in conjunction with 
mirrors, to illuminate other points; they are switched on in succession 
from a dial close to the cathetometer from which place the screens 
too can be adjusted to the desired height. For particulars as to the 
precautions adopted during the measurements we refer to the Com- 
munications already mentioned. 
$ 5. Calculation of experimental results, corrections. The dilato- 
meter was calibrated with mereury. For this purpose there was 
temporarily fused to dq (PL. II fig. 2) a small glass tap with a capillary 
that was immersed in a tray of mercury. The volume of the meniscus 
was allowed for from the data given in Comm. N°. 67 (Dec. 1900 and 
Jan. 1901); for most menisci it is sufficient to regard them as 
62 
Proceedings Royal Acad. Amsterdam. Vol. XIII. 
