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Proceedings of the Royal Society of Edinburgh. [Sess. 
also a decided fall in the value of v from that of the iodate of potassium 
or rubidium to that of chlorate of rubidium or caesium respectively. This 
is very clearly shown in the diagram (page 646), in which the heights of 
the columns are proportional to the values of v produced by the dissolution 
in 1000 grams water of y 1 ^ gram-molecule of the salts inscribed at their 
bases. The columns referring to the oxyhalides are shaded. 
One of the principal reasons for determining the specific gravity of 
solutions of the high dilutions used in this research was to ascertain whether 
the condensation which is commonly observed when a saline solution is 
diluted with water takes place when the concentration of the solution 
produced is continuously diminished. The difference between the sum 
of the displacements of the concentrated solution and the water used and 
that of the resultant solution produced is a question which has often been 
raised ; but it has hitherto been impossible to decide it, in the case of 
dilute solutions, owing to the disabilities and imperfections of the methods 
used for determining their specific gravity. 
One result of the observations made in this research is that in the case 
of the solutions of some salts there is a limit beyond which contraction 
does not take place on dilution, and some in which it is replaced by 
expansion. This is certainly the case with solutions of chloride of sodium 
which contain less than T \ gram-molecule of salt per 1000 grams of water 
at 19-5° C. 
A large amount of material bearing on this and other important points 
connected with the specific gravity and displacement of saline solutions has 
been collected in the course of the investigation, and much of it will be 
found to be discussed in the extended paper which is now in the press. 
( Issued separately October 24 , 1911 .) 
