1897 - 98 .] Note on certain Chemical Reactions. 
35 
ten seconds. With 36 per cent, the time required was about 4 
minutes, and with 30’5 per cent, acid, 15-20 minutes. 
Oxidation of nitric oxide by nitric acid . — Passing nitric oxide 
into nitric acid of 36 per cent., the blue colour of nitrous acid 
rapidly made its appearance, while nitric acid of 28 per cent, 
remained colourless. 
These examples are sufficient to indicate the nature of the reasons 
for assuming an increase in electrolytic conductivity as a common 
characteristic of all these reactions. Whenever the dilution of 
the acid is carried beyond that corresponding to maximum con- 
ductivity, the velocity of the reaction is reduced to a minimum, or, 
as in the case of sulphuric acid and cane sugar, the velocity of 
reaction in an opposite direction becomes the greater. It will be 
remembered that dilute sulphuric acid so far from de-hydrating or 
charring sugar, adds water on to it, or hydrolises it. 
It may be pointed out here as highly significant that those salts 
which are markedly deliquescent are also those whose saturated 
solutions gain considerably in electrolytic conductivity by dilution, 
and that those gases which form a cloud in ordinary air are also 
those whose saturated solutions have their conductivity greatly 
increased by dilution. 
One result of this investigation is the correlation of those re- 
actions which result in an increase of electrolytic conductivity 
and their differentiation from reactions in which there is a decrease 
of electrolytic conductivity. 
Chemical decompositions dependent on absorption of energy 
are not generally associated with increase of electric conductivity, 
but the reverse. Instances of this class of chemical change 
are : — 
{a) The separation of solvent from solute by evaporation. 
(b) The decomposition of compound bodies by electrolysis. 
(c) The decomposition of compounds by the action of heat. 
The great class of reactions included under the phrase “ the 
double decomposition of salts ” frequently do not result in a finally 
increased electrolytic conductivity, because of the precipitation of 
insoluble salts. 
In the reactions referred to above, as characterised by increase in 
electrolytic conductivity, the velocity of reaction is not proportional 
