— 215 — 
XVII, the least proportional difference of drop number, cans- 
ed by an alteration in the proportion of the liquids, is between 
T and B T 2 where a diminution of 33.33 per cent in the tur- 
pentol and an addition of 33.33 per cent of benzol causes a 
difference of 35 .3 in the drop number. 
Liquid 
T BT 2 BT 
B 2 T 
B 
Percentage . . 
" B 
. T 
0 33.33 50 
100 66.66 50 
66.66 
33.33 
100 
0 
Difference of") 
L B 
33.33 16.66 
16.66 
33.33 
Percentage. . J 
r t 
33.33 16.66 
16.66 
33.33 
Difference of' 1 
drop-number 
35.3 21.7 
24.3 
102.0 
Or this stalagmometer shows the composition of the liquid 
to within 1 per cent. Further if the mixture contains less 
than one-third of benzol its proportional composition can be 
determined, on an average, to within 0.33 per cent. 
It may be noticed wfith regard to SLL that the value of gt 
is of much less influence upon the drop size than in the case 
of SLG. It is generally sufficient in the former case that the 
average value of gt should be constant. This is especially the 
case when the drops are found from a tube (as the end of a 
syphon) and not from a convex solid. The reason is ob- 
viously that in the former case the thickness of the residual 
film upon which we have seen the drop-rate depend is at all 
rates indefinitely great while in the latter it depends upon 
the rate of supply. 
In order to compare the drop size of A through B with that 
of B through A under quite similar conditions : the syphon 
A of Fig X was inverted and applied to the cup stalagmometer 
of Fig. VIII. The arrangement of the end is seen in Fig. 
XI. In using this form of stalagmometer the end of the de- 
livery syphon must be at first wiped dry, so that the water 
may not creep back outside the syphon, and so give rise to an 
irregular base to the drop. Water was made to drop through 
A Fig. XI at the same rate gt~%” and through the same li- 
quids as before, to wit T, BT 9 . BT, Be T, B. The same 
