FOR DISTINGUISHING SACCHARINE JUICES. 595 
' 2nd. That the proportion of potash or of any other oxybase neces- 
sary to neutralize this acid being once known, it will not be necessary 
to have recourse to experiments to ascertain the quantity of the other 
oxybases which are capable of neutralizing the same acid, 
3rd. That the action of the acid upon organic colouring principles 
may be predicted with a great degree of probability. 
13. There are properties which, without having the importance of 
those which have been noticed, are interesting, inasmuch as they furnish 
useful indications. For instance, if a substance precipitates without 
alteration the animal matter of the water in which they are held in solu- 
tion, it may be inferred with great probability that it will preserve animal 
matter, as is the case with the tannins ; and I shall show that nearly 
all the substances of which this is predicable, though they may differ 
widely in their elements, have notwithstanding many analogous pro- 
perties ; among others a flavour more or less astringent. 
14. The properties which have been considered may be remarked 
(12 and 13), though under different relations, when a community of 
characters is endeavoured to be established between a greater or less 
number of chemical species, differing greatly with regard to their ele- 
mentary composition. Let us now examine the properties which are 
the best adapted for the definition of particular species. 
15. The properties the most suitable for this purpose are certainly 
those which are manifested for our observation with equal intensity in 
the different conditions in which the specimens of the species possessing 
them may be placed. For example, acidity, which we have considered 
as one of the most general properties of compound bodies, may become 
a specific character of precision when considered in an acid body in 
particular, with regard to the proportion in weight of the potash or any 
other alkali, that a given quantity of this acid requires in order to its 
neutralization. In fact this proportion will be constant as long as the 
specific nature of the acid lasts. 
16. Properties which are manifested by obvious planomena of easy 
production are also adapted to become specific characters; but I shall 
show that these characters are specific in proportion to the small amount 
of the alteration sustained by the elementary composition of the species. 
With this circumstance in view, I have formed three groups of che- 
mical properties from these three species: first, those which do not 
undergo any sensible alteration in their composition; secondly, those 
which undergo an alteration which does not prevent them from resuming 
their first composition ; and lastly, those in which the alteration is suffi- 
ciently profound to preventthe resumption of the original composition*. 
* Considérations générales sur l Analyse organique. Levrault, Paris, 1824. 
p. 34 to 42. 
Voi. I.—Parr IV. 28 
