104 REPORTS ON THE STATE OF SCIENCE.—1914. 
forms of such compounds are to be represented by a definite grouping 
of atoms, which in certain reactions passes over into an isomeric group- 
ing by a rearrangement of bonds consequent upon the displacement 
of a hydrogen atom ’; it was to express this view that the word ‘ desmo- 
tropy’ was introduced. If used in this sense, to describe the labile 
isomerism produced by the mobility of a hydrogen atom, it might be 
of real value; unfortunately the meaning of the word was tampered 
with by Hantzsch and Hermann (Ber. 1887, 20, 2802), and, as an 
inevitable consequence, it has become ambiguous, and has ceased to 
be clearly significant. 
Nearly all the cases to which the word ‘ tautomerism’ has been 
misapplied in recent years are examples of isomerism pure and simple, 
the only special feature being the fact that the isomerides can be 
conyerted into one another with greater or less ease. It is therefore 
very rarely necessary to use any other words than ‘ isomerism’ and 
‘isomeric change’ to describe the phenomena. Isomeric compounds 
which owe their lability to a mobile hydrogen atom might well be 
distinguished as ‘ desmotropic ’ but for the ambiguity arising from the 
ill-advised action of Hantzsch in attempting to extend the meaning of 
this term. At the present time the least ambiguous phrase that can 
be used to distinguish ethyl acefoacetate and its allies from the very 
much larger group of substances which exhibit ‘ dynamic isomerism ’ 
or reversible isomeric change is to refer to them as examples of ‘ keto- 
enol ’ isomerism, and in other cases to use some similar specific name, 
describing the nature of the two compounds between which a condition 
of equilibrium may exist. 
Isomeric Halogen-derivatives of Camphor. 
Another fruitful, though expensive, line of research has been opened 
out during the year by applying the process of dynamic isomerism to 
the preparation. of new halogen-derivatives of camphor. A new 
isomeride has been prepared from a-chlorocamphor by acting on it 
with alkali, in order to produce a condition of dynamic isomerism in 
the liquid, and then arresting the isomeric change by the addition of 
acid. On freezing the alcoholic solution, most of the original substance 
erystallises out,.and the mother-liquor contains the isomeric a-chloro- 
camphor. This melts at 117° (instead of 94°) and has [a],+41° 
(instead of +970). As the new compound can be prepared readily 
on a large scale, it promises to be of great value in studying the type 
of dynamic isomerism in which a catalvtic agent must be added 
deliberately in order to bring about a condition of equilibrium between 
isomers. The whole series of compounds which is now under investi- 
gation will provide valuable data for the study of dynamic isomerism 
and rotatory dispersion, and for the elucidation of the crystallographic 
structure of the camphor molecule. 
The Committee asks for reappointment with a grant of £40. An 
increased grant is asked for to cover the heavy cost of the organic 
preparations referred to in the last section of the Report. 
