Tad REPORT—1896. . 
\ 
holds good; therefore the equation om e(t— tov) (to—t), (2.), where ¢,, is the tem- 
perature to which the liquid was overcooled, ¢, is the freezing-point, holds good, 
z,e,, the velocity of reaction is directly proportional to the surface of the solid in 
contact with the liquid, and to the remoteness from the freezing temperature. The 
condition is t—t,,>0, z.¢., the solid solvent is present in the liquid, and the system 
is heterogeneous. 
4,. Velocity of melting of solid solvents in liquid solvents or solutions (¢.g., of 
ice in water or aqueous solutions), The velocity of ice melting cannot be 
measured with the same accuracy as the velocity of ice separation. The author 
has carried out experimental verification of the equation = =c(t,—t), where c is 
directly proportional to the surface of the solid in contact with the liquid, by using 
cubes of ice, whuse surface could be directly measured at the beginning and at the 
end of the reaction, and during the reaction it could be calculated from the fall of 
temperature of the investigated liquid. 
5. Velocity of crystallisation of oversaturated solution (equilibrium between 
separated salt and salt solution), The equation (2.) holds good—z.e., the velocity 
of reaction is directly proportional to the surface of the salt in contact with the liquid 
and to the amount of oversaturation (not to the total quantity of the salt dissolved). 
This very remarkable fact throws light on the meaning of the velocity of reaction 
before perfect equilibrium, Let us assume that the total quantity of the salt dissolved 
takes place in the reaction, then our equation will be = =c(t,—t)A, where ¢t,—¢ 
as 
is directly proportional to the surface of the separated crystals, A is the concen- 
tration of the liquid part of the time z. This equation can be written in the form 
eels —t) (A’+a), where A’ is the concentration at equilibrium and a is the 
amount of oversaturation at the time z. Now c(t, —t)A’=0 independently of the 
value ¢, —¢, since the concentration A’ is in equilibrium with any quantity of the 
salt present in the liquid. The only equation for the reaction is therefore 
= =e(¢,—t)a—ve., the equation given above. 
Since in the case of perfect equilibrium one of the parts of the heterogeneous 
system can completely disappear (with the change of the temperature or of the 
pressure of equilibrium), it follows that above or below the point of equilibrium 
4 ; : dt ie! 
no opposite reaction occurs, and because of this when 5 becomes zero, the equili- 
brium is a static one (and not a dynamic one, as assumed). 
‘We thus find that one and the same equation represents the relations of all 
investigated reactions before perfect equilibrium. The equation is therefore 
general, and must be put at the basis of all other reactions of more complicated 
form (which will form the subject of further investigation). 
Static equilibrium because of the interference of other factors is never in reality 
reached in nature. The equilibrium is never real or perfect, but only apparent. 
A detailed investigation of this in the case of equilibrium between ice and water 
or solution is given in the author’s paper ‘On the real and apparent freezing-point 
and the freezing-point methods.’ This gives us the possibility of explaining some of 
the most important phenomena in nature, &c., as the formation of glaciers, icebergs, 
snow, the melting processes, &c. All these phenomena never completely reach 
the dead-point of perfect equilibrium, but a continuous change or reaction takes 
place in nature, 
6. The Behaviour of Litmus in Amphoteric Solutions. 
By Tuomas. R. Brapsnaw, B.A., ILD. 
Solutions which redden blue litmus, and at the same time turn red litmus blue, 
are said to have an amphoteric (dug@o répas) reaction. This reaction is always 
