G. F. Becker—Correction for Vacuum in Chemical Analysis. 267 
consequently need no correction. As may be seen from the 
figure, if platinum weights are employed, no substance the 
specific gravity of which exceeds 7-8 requires correction, i 
one-tenth of a milligram be regarded as an insignificant error. 
For brass weights the error is less than one-tenth milligram for 
all known specific gravities above 5:02. 
: les are usually weighed with both platinum and brass, the 
integral gram weights being made of the latter metal and the 
for ten grams, it is convenient to omit small quantities from 
calculation. Three errors in the correction for vacuum have, 
of a gram with platinum weights, and the error caused by 
neglecting the correction for small fractions of a gram. The 
Sum of these errors must not exceed one-tenth of a milligram, 
