maximum combination with nitroxy-groups, the product was dissolved in
concentrated nitric acid, and the solution poured into sulphuric acid.

The following analytical results were obtained (a) for the product
obtained directly from the fibrous benzoate and purified as indicated,
(b) for the product from the further treatment of (a) as described:

Found Calc. for
(a) (b) Dinitrate Trinitrate
dinitrobenzoate dinitrobenzoate
Total Nitrogen 7.84 8.97 7.99 9.24
O.NO_{2} " 5.00 5.45 4.00 5.54
NO_{2} (Aromatic) 2.84 3.52 3.99 3.70

With the two benzoyl groups converted into nitro-benzoyl in each
product, the limit of the ester reaction with the cellulose residue is
reached at the third OH group.

The nitrogen in the amidobenzoate resulting from the reduction with
ammonium sulphide was 4.5 p.ct.--as against 5.0 p.ct. calculated. The
moisture retained by the fibrous nitrate--nitrobenzoate--in the air-dry
state was found to be 1.97 p.ct.

The product from the structureless dibenzoate or tetrabenzoate on the
C_{12} formula, was prepared and analysed with the following results:

Calc. for
Mononitrate tetranitrobenzoate
Total Nitrogen 6.76 7.25
O.NO_{2} " 1.30 1.45
NO_{2} " (Aromatic) 5.46 5.80

The results were confirmed by the yield of product, viz. 131 p.ct. as
against the calculated 136 p.ct. They afford further evidence of the
generally low limit of esterification of the cellulose molecule. From
the formation of a 'normal' tetracetate--i.e. octacetate of the C_{12}
unit--we conclude that 4/5 of the oxygen atoms are hydroxyl oxygen. Of
the 8 OH groups five only react in the mixed esters described above, and
six only in the case of the simple nitric esters. The ester reactions
are probably not simple, but accompanied by secondary reactions within
the cellulose molecule.

* * * * *

(p. 34) ~Cellulose Acetates.~--In the first edition (p. 35) we have
committed ourselves to the statement that 'on boiling cotton with acetic
anhydride and sodium acetate no reaction occurs.' This is erroneous. The
error arises, however, from the s