ON THE CONSTITUTION OF SALTS. 
347 
oxide of lead, barytes, and the other metallic oxides included in 
or related to the magnesian family, appear to rival water 
(which is a member of the same family) in the frequency 
with which they discharge this function in the constitution 
of saline compounds, particularly of those belonging to the 
organic kingdom. Thus, the neutral organic principle orcine 
combines with five atoms of oxide of lead, according to 
Dumas, which replace five atoms of water, which orcine other- 
wise possesses. But it should be brought prominently into 
view, that neither the water nor the oxide of lead is basic in 
these compounds, but superadded to the orcine, like constitu- 
tional water, — a distinction which is well expressed in their 
formulae, by placing the symbols for water and oxide of lead 
after, and not before, that of orcine, or in the proper place for 
water of crystallization in the formula of a salt. Potash, soda, 
oxide of silver, and oxide of ammonium, on the other hand, 
are never found in this relation to a salt, or discharging any 
other functions than that of base to an acid. Hence, there are 
no such compounds as sub-salts of these bases. In Peligot's 
late admirable paper on the varieties of sugar (" Annales de 
Chimie," &c, torn. 67, p. 113,) he has formed the compounds 
of that principle with barytes, lime, oxide of lead, and common 
salt, and determined their composition with great accuracy. 
Like preceding chemists, he considers them as salts, in 
which sugar is the acid, and the metallic oxide the base, and 
continues to speak of them as saccharates, although with an 
evident reserve. But the conclusion is by no means neces- 
sary, that sugar is an acid, and that the lime, oxide of lead, &c, 
are basic to it. On the contrary, sugar being a body neutral 
to test paper, is more likely to be a salt than an acid. That 
the metallic oxide attached to it discharges the function of the 
superadded water of crystallization of so many bodies, appears 
to me evident from the following circumstances: — 1. It is se- 
parated from the sugar by the weakest acids, even by carbonic 
acid. 2. It replaces water in the sugar, which water can also 
be replaced in part by an equivalent proportion of chloride of 
sodium, or by the hydrates of barytes and lime. Now, basic wa- 
ter is never replaced by a salt, although constitutional water fre- 
