316 REPORT—1890. 
Secondly, as to the influence of the strength of the solution. It is 
remarkable that although the osmotic pressure theory depends on the 
behaviour of solutions below a certain strength, no attempt whatever has 
been made by its supporters to obtain any data respecting such solutions. 
The data on which their views were founded referred to solutions 
considerably stronger than the requisite ‘gas strength,’ and though, no 
doubt, it was convenient to work with data which afforded a ready excuse 
for any awkward irregularities which might be met with, such data must 
lack the conclusiveness which is so eminently desirable. The few data 
which I have accumulated as to solutions of an ‘ideal’ strength can 
leave no doubt that, even in their case, the depression is not a constant 
independent of the strength. 
A solution of sulphuric acid containing ‘(0O8H,SO,, 100H,O would be 
of a strength comparable with the gas from the acid if it could be 
Fic. 1.—Deviation from regularity of the freezing points of very weak solutions. 
06 08 
Molecules dissolved in 100H,0. 
gasified at normal pressure and temperature, and the molecular depres- 
sion should be constant for all solutions below this strength: it should 
be represented by a horizontal line such as AB in fig. 1, whereas the 
observed deviations from constancy are very great, being represented by 
the lines marked H,SO,; and, moreover, these deviations are by no 
means regular, and cannot therefore be attributed to imperfect gasifica- 
tion ; they possess none of the characteristics of the deviations of gases 
from Boyle’s law. The determinations on which these results are based 
are very numerous; there are about sixty experimental points on the 
portion here shown, and the mean error of each point as determined in 
two different ways was only 0°-0005, a quantity represented by one-tenth 
of one of the divisions of the paper; the deviations from regularity 
amount to thirteen times this quantity, and to as much as 16 per cent. of 
the total depression measured. 
The other lines in fig. 1. represent the deviations from regularity in — 
3 
z 
