258 T.S. Hunt on the Theory of Types in Chemistry. 
N 
of nitrogen and six of hydrogen, which being reduced to one- 
third corresponds to a triple molecule, M,M,, so that these three 
types and their multiples are reducible to that of hydrogen more 
or less condensed.—(Wurtz, Ann. de Chimie et de Physique, [3], 
xliv, 302.) 
As regards the rejection of water as a type of organic com- 
pounds and the substitution of carbonic acid, founded upon the 
consideration that these bodies in nature are derived from C,0,, 
Wurtz has well remarked that water, as the source of hydrogen, 
is equally essential to their formation, and farther that the car- 
bonic anhydrid, like all other anhydrous acids, may be regarded 
as a simple derivative of the water type. Having then adopted 
the notion of referring a great variety of bodies to a mincr 
ies of simple constitution, water is to be preferred to car- 
bonic acid, Ist, because we can compare with it many mineral 
compounds which can with difficulty be compared with carbonic 
acid, and 2d, because the two atoms of hydrogen in water being 
replaceable singly, the mode of derivation of a great number of 
compounds (acids, alcohols, ethers, etc.) is much more simple 
and natural than from carbonic acid. As Wurtz remarks, Kolbe 
has so fully adopted the theory of types that he wishes to roulti- 
plication that it is worthy “to form the basis of a system of 
oe (Repertoire de Chimie Pure, 1860, pp. 856-359.) 
monia as typical forms, but even look upon water as the deriva 
tive of hydrogen, which is itself the primal type. 
