190 On Iodine. [Serr. | 
acidity is not exact, and that there is a great difference between the 
property which an acid has of neutralizing a greater or smaller 
quantity of base, and the energy of its acidity. Iadmit this for an 
instant ; and I shall even suppose that the acid energy of a body 
depends upon its electric energy. Do we not admit that the electric 
energy of a neutral salt is null, or almost null? And even in this 
case, must not the electric energy of the acid be destroyed by the 
opposite energy of the base? Jf this were the case, it would be 
doubtless as remarkable to see the same quantity of base, the electric 
energy of which is constant, neutralize the energy of very different 
acids, which without doubt is variable. Besides, I must observe 
that M. Berthollet has long ago put it out of doubt that the insolu- 
bility and elasticity, both of the acids and bases, and of the com- 
pounds into which they enter, are the principal causes of their 
mutual decompositions ; and consequently that the electric energies, 
though highly worthy of consideration, are here but secondary. 
But I shall venture to say that the neutralization of acids and alkalies 
in simple ratios, and that of their electric energies, when they form 
neutral salts, are subordinate to the property which all bodies have of 
combining in definite proportions ; and I conceive that what we call 
neutrality does not indicate a uniform degree for all combinations. 
A compound is neutral with respect to us when it refuses to unite 
with the acid or alkaline particles presented to it. But if the energy 
of the acid body which enters into the compound does not exactly 
correspond with the energy of the alkaline body ; if it be necessary, 
in order to saturate the excess of the one or the other, to add a 
quantity of acid or alkali beyond the definite proportion in which 
the acid and alkaline body can combine, the combination of the 
portion added will not be possible, and consequently the saturation 
of the acidity or alkalinity cannot be complete, though re-actives 
indicate the contrary. Such combinations ought to preserve a cer- 
tain energy of affinity, which is probably the cause of the formation 
of triple salts, and these salts ought to approach nearer to perfect 
neutrality than those of which they are formed. We observe, in 
fact, that the solubility of the triple salts is in general less than that 
of the salts of which they are composed; and it is natural to think 
that, ceteris paribus, a saline combination ought to be the less 
soluble the more neutral it is. 
From what has been said, we see that oxygen in general gives 2 
‘ neutral, acid, or alkaline, character toa body according ta the pre- 
portions in which it combines with it ; but that the condensation of 
volume which the constituents undergo, has, independent of pro- 
portions, a very great influence in the determination of the cha- 
racter of the compound which they form. ‘Thus the combination in 
volume of two parts of hydrogen, azote, or carbon, with one of 
oxygen, and a condensation of one-third of the total volume deter- 
mines the neutral character. ‘The combination of one part in vo 
lume of carbon or sulphur with one part of oxygen, and a conden- 
sation of half the total volume, determines the acid character. But 
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