wn, with production of "humus," a complex of colloidal
"unsaturated" bodies of acid function, they fulfil important chemical
functions by interaction with the mineral soil constituents.

_Chemistry of Cellulose._--Purified cotton cellulose, which is the
definitive prototype of the cellulose group or series, is a complex of
monoses or their "residues." It is resolved by solution in sulphuric
acid and subsequent hydrolysis of the esters thus produced into
dextrose. This fundamental fact with its elementary composition, most
simply expressed by the formula C6H10O5, has caused it to be regarded as
a polyanhydride of dextrose. Forming, as it does, simple esters in the
ratio of the reacting hydroxyls 3OH: C6H10O5, and taking into account
its direct converson into [omega]-brom-methyl furfural (Fenton) a
constitutional formula has been proposed by A.G. Green (_Zeit. Farb.
Textil Chem._ 3, pp. 97 and 309 (1904)), which is a useful
generalization of its reactions, and its ultimate relations to the
simpler carbohydrates, viz.,

CH(OH).CH.CH(OH)
| >O >O
CH(OH).CH.CH2 .

Green considers, moreover, that a group thus formulated may consistently
represent the actual dimensions of the reacting unit, but that unit of
larger dimensions, if postulated, is easily derived from the above by
oxygen linkings.

From another point of view the unit group has been formulated as

/CH(OH).CH(OH)
CO >CH2
\CH(OH).CH(OH) ,

the main linking of such units in the complex taking place as between
their respective CO and CH2 groups in the alternative enolic form
CH-C(OH). This view gives expression to the genetic relations of the
celluloses to the ligno-celluloses, to the tendency to carbon
condensation as in the formation of coals, and pseudo-carbons, to the
relative resistance of cellulose to hydrolysis, and its other points of
differentiation from starch, and more particularly to the ketonic
character of its carbonyl (CO) groups, which is also more in harmony
with the experimental facts established by Fenton as to the production
of methyl furfural.

The probability, however, is that no simple molecular formula adequately
represents the constitution of cellulose as it actually exists or indeed
reacts. On the other hand, it has been suggested that cellulose is to be
regarded as representing a condition of matter analogous to that of a
saline electrolyte in solution, i.e. as a complex of molecular
aggregates, and of r