116 Dulong and Petit onthe Measure of Temperatures, [Fus: 
which may be seen in the following table, approach very nearly 
to those of the memoir above quoted, in the temperatures com- 
mon to the two tables. But the following embraces almost the 
complete scale of mercury from the freezing to the boiling point 
of the liquid,. which is an interval of about 400°. 
TABLE I. 
Temperature indicated Corresponding volumes Temperature indicated by an air 
by the mercurial ther- of the same mass of thermometer, corrected for the 
mometer, ‘ air. dilatation of the glass. 
PSG AR 8 O°B6500% 25) OU, FE BOOP 
Ors, mene. 1 O08 sercoe ER 0-00 
100 ... + WL SISO os OS aes 100-00 
Lottie tins: Oa Sed DHIG Ure. APP 148-70 
QOOE IS ee Pee 1FSBO se NORE ne OE 
eh ty Ke. Ha (OLOO CLLR we. 924505 
BOOMS Pos ye DOO: ah RY, Be 
360 } mem. $2 81ZD cess perce ee 800-00 
The temperatures, indicated in the last column, have been 
corrected for the dilatation of the glass, which we shall imme- 
diately point out. 
There exists a very great disagreement among the numbers 
given by different philosophers for the boiling point of mercury. 
This depends in part upon the greater or smaller care bestowed 
by each upon the construction of his instruments, and upen the 
accuracy of the correction which it is necessary to make for the 
portion of the tube which is not plunged in the liquid. The 
method which we have employed dispenses with this correction. 
Instead of measuring immediately the augmentation of volume 
of the same mass of mercury, as 1s done in the ordinary thermo- 
meters, we have determined the loss of weight which a mass 
of mercury, capable of fillmg a glass at zero, sustains when 
completely plunged into boiling mercury. Knowing the apparent 
dilatation of mercury in glass for the first 100°, we can, by a very 
simple calculation, find the corresponding temperature on a 
mercurial thermometer, whose tube is at the same temperature 
as the bulb. To prevent the liquid contained in the vase from 
boiling, the precaution was taken to make it terminate in a very 
nairow vertical tube, six centimetres in, length. The liquid 
column, which it contained, did not make the 6000th part of 
the total mass ; but by the pressure which it exercised in the 
interior of the vase, it completely prevented the formation. of 
vapours. It is needless to say that great care was taken to 
expel every trace of air or humidity. 
its way by little and little into the tube fill the bath has reached the temperature of 
the air. The calculation is then the same as in the case of air; and the only tem- 
perature to measure is the maximum, which may be obtained with the greatest 
precision. 
