344 THE EARL OF BERKELEY, MESSRS. E. G. J. HARTLEY AND C. V. BURTON: 
hence 
_ f' r " 
SP = I v dp, 
A'jr 
where s is the mean value of s over the range of 1 to 1 + P. If Boyle’s law is true 
for the vapour in air we get 
P = log, tt'o/tt^x RT/s,.(6) 
ancl modifying this in conformity with (4) we get 
P = log, \!A-{IA- 1K/B] x RT /s, .(7) 
where [Z 0 A-(^i-l K/B] = Po / Pl = tt'o/t4. 
The osmotic pressures calculated by means of (7) are given in Tables XIII. and 
XIV., in which column (l) gives the weight concentrate. Columns (2) and (5) the 
values of lo g e p 0 /pi obtained as a weighted mean value of the numbers in column (ll) 
of the previous tables. Columns (3) and (6) the values of s used in the calculation, and 
(4) and (7) the resulting osmotic pressures. Column (8) gives such osmotic pressures 
as have been observed directly ; these are the results tabulated in ‘ Roy. Soc. 
Proc.,’ A, vol. 92, 1916, pp. 483-484, reduced to the new concentrations. 
Unfortunately, in tha.t paper, by an oversight, the following two “direct” osmotic 
pressures were omitted :— A solution of cane sugar of weight concentration 56'631 
gave an osmotic pressure of 43'95 atmospheres, another of weight concentration 
Table XIII.—Cane Sugar. 
(!•) 
(2.) 
(3.) 
(4-) 
u> 
(6.) 
(7.) (8.) 
At 30° C. 
At 0° C. 
Weight 
Calculated 
Calculated Direct 
eoncentra- 
lo ge Po/Pi- 
5 
osmotic 
log* po/Pi- 
s. 
osmotic osmotic 
tion. 
pressure. 
pressure. pressure. 
atmospheres. 
34-00 
0-01950 
1-00287 
26-82 
— 
— 
— — 
56-50 
0-03429 
1-00103 
47-25 
0-03516 
0-99515 
43-91 43-84 
81-20 
0-05256 
0-99873 
72-59 
0-05380 
0-99157 
67-43 67-68 
112-00 
0-07762 
0-99554 
107-55 
0-07983 
0-98690 
100-53 100-43 
141-00 
0-10305 
0-99176 
143-33 
0-10669 
0-98321 
134-86 134-71 
183-00 
0-14231 
0•98653 
198-98 
0-14711 
0-97842 
186-86 
217-50 
0-17586 
0-97360 
249-16 
0-18080 
0-97399 
230-70 
243-00 
— 
— 
— 
0-20666 
0-97117 
264-46 
