504 
PHYSICS: W. W. COBLENTZ 
NOTE ON THE COEFFICIENT OF TOTAL RADIATION OF A 
UNIFORMLY HEATED ENCLOSURE 
By W. W. Coblentz 
BUREAU OF STANDARDS. WASHINGTON. D. C. 
Communicated by R. A. Millikan, June 25, 1917 
In a recent communication^ I gave an estimate of the probable value 
of the coefficient of total radiation of a uniformly heated enclosure, or 
'black body' (Stefan-Bolzmann constant). 
It was shown that by making corrections for atmospheric absorption, 
the data obtained by various observers were of the order of 
(T = 5.7 X 10-12 ^att cm.-2 deg.-4. 
My own value was given as 
a = 5.72 X 10-12 ^att cm.-2 deg.-^ 
It was obtained by applying a correction of 1.2% for losses by diffuse 
reflection from the receiver used in evaluating the radiant power in 
absolute measure. Nine receivers were used, some of which were 
covered with lamp black and some with platinum black. 
During the past winter further consideration was given (1) to the 
correction for the loss of energy by diffuse reflection from the receiver 
and (2) to the question of atmospheric absorption. 
In view of the important conclusions arrived at by MilHkan^ as to 
the value of this constant, as the result of his further investigations of 
the value of the electron e, it seemed of interest to record herewith 
recalculations and new experimental verifications of the data on the 
radiation constant, just mentioned. 
In the recalculations a correction of 1.2% was applied for losses by 
reflection from receivers covered with lamp black (soot) and a correction 
of 1.7% for losses by reflection from the receivers covered with plati- 
num black. These corrections were determined by direct experiment 
upon some of the receivers and by comparison of the surfaces of the 
other receivers with samples of lamp black whose reflection losses had 
been determined in a previous investigation.^ 
The recalculated value is 
cT = 5.722 = 10-12 ± 0.012 watt cm.-^ deg.-^ 
which is practically the same as previously obtained. 
The correction for atmospheric absorption of dry air was determined 
by observing the transmission through a brass tube 6 cm. in diameter 
