Can ele- 
mentary 
bodies be 
isomeric ? 
210 SEVENTH REPORT—1837. 
one change commencing as it were where the other ends, and 
basing itself upon it. 
67. Thereare other analogies also between these two doctrines. 
Isomerism like dimorphism is dependent on circumstances, is 
developed in certain cases by change of temperature. Thus ac- 
cording to Lowig* the racemic (paratartaric) acid is changed 
into the tartaric by simple fusion. The crystals of anhydrous 
cyanuric acid (3Cy+60+3H) distilled at a heat below redness 
into a vessel cooled to the freezing temperature, gives a liquid 
hydrated cyanic acid 3 (CyO + HO), which on attaining the tem- 
perature of the air changes into a colourless solid—the inso- 
luble cyanic acid. During these changes there is no escape or 
loss of any of the elements. The polymeric carbo-hydrogens 
seem to change into one another, in a certain order, by an ele- 
vation of temperature; the sugars, gums, and starches also 
pass into each other by a slight alteration of circumstances, 
and future observation will doubtless make us acquainted with 
the conditions necessary for the production of the several mem- 
bers of the known and of many other as yet unknown isomeric 
groups. 
68. Connected as these two classes of phenomena seem to be 
in their probable origin, and by the kind of circumstances under 
which they are developed, they may be expected to throw some 
light on each other. Thus if substances may appear in more 
than two or three isomeric states, be isotri or tsopolymeric, why 
may they not also be ¢7i or polymorphic? In whatever degree 
we consider these two classes of appearances to be analogous, 
in the same degree will be strengthened the probability we have 
already seen to exist, that the forms which the same body may 
assume are not limited to two or even three. 
69. Again, if simple substances, like sulphur and carbon, 
may assume two incompatible forms, may they not present 
themselves in two isomeric states? If they are susceptible of 
that internal molecular change to which dimorphism is due, why 
not also of that deeper change, as we suppose it, to which iso- 
merism is owing—by which difference in chemical relations is 
produced ? 
An affirmative answer to this question will probably be the 
next great step in chemical science, advancing the knowledge 
of our time at least as far as the discovery of the alkaline me- 
tals carried forward the chemistry of the time of Davy. 
70. Meanwhile the probability of such a discovery does not 
rest merely on a supposed analogy between the phenomena of 
* Pog. An., xiii. p. 588. 
