250 
MK. J. J. MANLEY ON THE APPARENT 
Table V. 
Date. 
N umber 
of deter¬ 
minations. 
Reduced R.P. values. 
Maximum. 
Minimum. 
Differences. 
Variation in 
weight. 
Mean. 
mgr. 
September 28, 1911 
21 
108-7 
105-0 
3-7 
-082 
106-8 
„ 30 „ 
12 
111-5 
109-8 
1-7 
-032 
110-7 
October 2 „ 
6 
107-0 
106-6 
-1 
-009 
106-8 
Oil the morning of October 3, the vessels were in succession removed from the balance 
and held by a suitably designed lifter whilst they were very lightly and quickly 
re-dusted witli silk ; the operation was so efiected that there was practically no risk 
of producing an appreciable rise in the temperature of their contents. Before the vessels 
were re-introduced the balance pans were also re-dusted and the whole apparatus 
arranged as before. The weighings were commenced an hour after the beam had been 
released and repeated at moderately short intervals throughout the day. Three 
independent determinations of the R.P. were made upon each occasion, and each of 
these was calculated as in the preliminary experiments from 5 observations of the 
extreme positions of the pointer ; the mean value of the 3 determinations was accepted 
as the true one, and this was then reduced as before for the standard temperature 
of 16° C. 
Proceeding in this manner we obtained in the course of 9 hours 20 groups of 3 B.P. 
values ; from these again were calculated 20 mean values, from which a final mean 
value for the relative weights of X and Y, before mixing the contents of either, was 
deduced. An actual example will serve to illustrate tlie method of procedure 
adopted— 
Example. 
Group. 
Time. 
R.Ps. 
Temperature. 
R.P. at 16“ C. 
No. 1 
11.10 a.m. 
119-6 
119-4 
119-3 
119-4 
10-8 
106-9 
The'chief points of interest associated with the 20 groups of determinations may be 
conveniently set forth as follows :— 
The Final Mean value deduced for the R.P. = 107’0. Of the 20 mean values 
obtained during the day the maximum value equalled 107'3 and the minimum value 
106'5 ; 10 of the 20 mean values were greater than the final mean and 7 were smaller; 
the remaining 3 values were equal to the final mean. The mean q- difierence was 
