194 
Book III. 
Neutraliza 
tion 
AFFINITY. 
not be saturated by others. Thus water is capable of 
combining with any quantity whatever of sulphuric a 
cid, nitric acid, and alcohol ; and all bodies seem capable 
of combining with almost any quantity whatever of ca 
loric. Several of the metals, too, are capable of com 
bining with any quantity whatever of some other me 
tals. In general, it may be said that those bodies called 
solvents are capable of combining in any quantity with 
the substances which they hold in solution. Thus wa 
ter may be added in any quantity, however great, to 
the acids, and to the greater number of salts. 
2. If we take a given quantity of sulphuric acid di 
luted with water, and add to it slowly the solution of 
soda by little at a time, and examine the mixture after 
every addition, we shall find that for a considerable time 
it will exhibit the properties of an acid, reddening ve 
getable blues, and having a taste perceptibly sour: but 
these acid properties gradually diminish after every ad 
dition of the alkaline solution, and at last disappear al 
together. If we still continue to add the soda, the mix 
ture gradually acquires alkaline properties, converting 
vegetable blues to green, and manifesting an urinous 
taste. These properties become stronger and stronger 
the greater the quantity of the soda is which is added. 
Thus it appears that when sulphuric acid and soda are 
mixed together, the properties either of the one or the 
other preponderate according to the proportions of each ; 
but that there are certain proportions, according to 
which, when they are combined, they mutually destroy 
or disguise the properties of each other, so that neither 
predominates, or rather so that both disappear. 
When substances thus mutually disguise each others 
properties, they are said to neutralize one another.