372 Mr Fenton , Oxidation in Presence of Iron. 
This semi-aldehyde is of especial interest in consequence 
of its relationship to uric acid, since its aldehyde-hydrate 
CH (OH) 2 . CO . COOH may he regarded as tautomeric with 
trihydroxy-acrylic acid C(OH) 2 = C(OH) . COOH. 
Oxidation of Carbohydrates. 
[Cross and Bevan, Trans. Chem. Soc. 1898. 463, 1899. 747. 
Morrell and Crofts, ibid. 1899. 786, etc.] 
This branch of the research has hitherto been undertaken, in 
communication with the author, especially by Messrs Cross and 
Bevan, and Morrell and Crofts. Amongst the most important 
results which have been obtained in this direction may be 
mentioned the observations of the latter chemists, who shew that 
both dextrose and lsevulose when oxidized by hydrogen dioxide in 
presence of ferrous iron yield hexosone CH 2 OH(CHOH) 3 . CO . CHO, 
and that similar results are obtained with arabinose and rhamnose, 
which give pentosone and methyl-pentosone respectively. 
Galactose, presumably owing to its special configuration, gives 
a different result, which is being further investigated. 
Messrs Cross and Bevan have also studied the action on 
acetylene and benzene, which yield acetic acid and phenol respec- 
tively. Furfural also yields a colour-giving substance, which is 
probably hydroxy-furfural. 
Function of the Iron. 
In the present state of these researches, which are still in 
active progress, it is somewhat premature to draw general con- 
clusions as to the probable nature of the influence of iron in the 
oxidations mentioned, but the following statements may be made 
with considerable confidence : 
(a) The influence of the iron belongs to the class of chemical 
changes usually described as catalytic, an almost infinitesimal 
proportion being in many cases sufficient to determine the 
oxidation. 
( b ) It is probably essential in all cases that the iron should 
be present in the ferrous state, and in the few instances where 
a ferric salt has been successfully employed it is probable that 
previous reduction to the ferrous state initially occurs. 
(c) Judging from the colour changes and other effects it is 
highly probable that the iron undergoes alternate changes in 
state of oxidation or valency ; the higher state may be the ferric 
condition or it may correspond to a still higher form, such as Fe0 2 . 
(Compare Manchot, Zeit. Anorg. Chem., 1901, 420.) 
