CHEMICAL AND PHYSICAL NOTES. 103 
tube D has an internal diameter of 7 mm., and the entry tube E 
has also 7 mm. diameter, or slightly less. The dry salt is intro- 
duced into C B; the thermometer passes through a cork at A, and 
the bulb is covered by the salt at the bottom of C B. The tube 
is then weighed. It is then connected with the steam generator 
and steam blown through, which in a few minutes produces a magma 
of boiling brine mixed with salt, while the thermometer takes the 
maximum temperature, and retains it until the solid salt approaches 
complete solution. 
The graduation of the thermometer thus receives a useful check 
at this part of the scale. If it is wished to verify the thermometer 
at any temperature intermediate between 100°C. and 108°°40C,, 
steam can be passed through until the temperature of the boiling 
solution has fallen to the degree wished, and by weighing the 
apparatus, or determining the chlorine, the amount of steam con- 
densed is found; and, as that of the salt is known, the strength of 
the solution, which boils at this particular temperature, under the 
observed barometric pressure, is obtained, and that temperature can 
always be again recovered independently of the thermometer with 
which the original observation was made. 
The elevation of the boiling-point of a saturated solution of a salt 
above that of pure water is affected by the barometric pressure. For 
