G. F. Becker—Correction for Vacuum in Chemical Analysis. 269 
and should it be erroneously supposed that the gram weights 
used were of brass, the total error in the correction would lie 
between 
— 0°000012 and 
+ 0:000187 with a mean value of 
+ 0:000087. 
arising from the neglect of the correction for small fractions. 
e influence of changes of 
temperature on the correction  orrection of the weight of a Hr for 
vacuum. 
r 
(Platinum weights.) 
caused by temperature from 
the correction as calculated for 
15°, a,; then 
&,=C, (t* 000366) (-— ;) 
ll 
G being the weight of oue 
cubic centimeter air at 0°, and 1 
¢ the variation of the tempera- 
ture from 15°. The value 2, 
will be at a maximum for spe- 
cific gravities above 1 when 
y=1landd=21-5. Accurate 
investigations are scarcely like- 
ly to be undertaken below 5° 
B 
PEEL 
1 
“0 1°11°21°3 Mg. 
Q conclusion, attention may be drawn to the fact, which 
appears very plainly in the table, that for the purposes of the 
reduction of weighings to vacuum, no very accurate determin- 
ation of the specific gravity is necessary. | 
keley, California, May, 1878. 
