234 MEASUREMENT OF HIGH TEMPERATURES. Ibull.1 
grams (Figs. 41 and 42) the data so obtained are small, being not larg( 
than 905° in the one case and 916° in the other. These values are 
be finally corrected by the value for v Ql found after the completion of 
the measurements by direct water calibration. I may remark in pass- 
ing, that the stem correction is negative, and that I applied a value! 
which is certainly not too large. Hence the stem error has produced! 
no erroneous negative increment of the value of T. 
In the case of Bulb T, the datum v is accepted as 280 cc , an approxi- 
mate value to be subsequently corrected for permaneut changes of vol! 
ume, etc. By the volumetric method (page 214) the volume of bulb, steml 
and capillary tubes is found to be 280.73 cc at the mean temperature 20o| 
From this is to be deducted the volume of the metallic capillary stems! 
0.40 cc ; the volume of the porcelain capillary stem, 0.53 cc ; and thel 
amount of dead space at the joints of the tubes, 0.23 cc . This leaves foil 
the volume of the bulb at 0°C. 
i' =279.58 cc . 
The same volume was measured at the close of the work by direct cali* 
bration with water, and found to be 
^0=279.06°°. 
This difference of 0.52 cc is due to the imperfection of the volumetric 
method in its present form. Preferring the latter value, the volume in-j 
crement for Bulb I is 
dv=-0M (I) 
In the case of Bulb II, v is accepted in the computations provisorilyr 
as v =279.3 cc , and found by direct calibration with water to be 
tf =278.73 cc . 
Hence for Bulb II 
<?0 O =— 0.57 (II) 
If now the formula, page 229, viz : 
be applied with the purpose of correcting the above approximate value! 
for the boiling point of zinc, it appears since T=910°; Ti=25° 
/(T 1 )=0.916; ??=279 cc ; ^=220 cc ; (l+aT) 2 = 19.2; that 
ST= 4-12.50 f or Bulb I, and 6T=+ 7.6° for Bulb II. 
In place of the single data obtained from Figs. 41 and 42 it is pref- 
erable to determine the values of T for each series. This is done inl 
Table 78, in whiclf, moreover, the data for increasing and decreasing! 
(888) 
