214 SEVENTH REPORT—1837. 
understand the researches of Mitscherlich, that some at least 
are qualified to go forward in the same path with himself, yet 
no one has ventured to shoot out into the main current of his 
inquiries or to dispute with him the honour of leading the ad- 
vance. It is certain indeed that in al/ the necessary qualifica- 
tions,—in knowledge of the subject, andin devotion toits advance- 
ment, as well as in intellectual gifts and acquirements, no living 
philosopher could replace the present leader. Could any other be 
expected to prosecute it so zealously as he whose mind has given 
it birth? 
We may be permitted therefore to wish and hope that the 
labours of this distinguished observer may be long continued to 
us, that he may win new laurels to himself and add new domains 
to the sciences he has already so greatly enriched. If the pre- 
sent report make his discoveries more familiar to the rising phi- 
losophers of our own country, or lead into the field of dimorphism 
one mind yet undecided what path of science to choose, its main 
objects will not be wholly unattained. 
Desiderata.—1. To determine the physical differences which 
exist between the incompatible crystals of the same dimorphous 
substance. (See blanks in Tables I. and IV.) 
2. Within what limits of temperature is each form stable ? 
within what other (?) limits may each form exist. (61.) ? 
3. In general we are acquainted only with the final result of 
crystallization: do bodies not pass through (so to speak) one 
or more forms as they crystallize till they ultimately assume 
one more stable than the rest? The microscope will aid this 
inquiry. (60.) 
4. In isomorphous groups of which one member is dimor- 
phous, to observe if, under certain circumstances hitherto neg- 
lected, the other members may not also be dimorphous. If 
mineral substances, specimens from different localities should 
be studied and measured. (20.) 
5. In groups represented by like chemical formule,—but 
the several members of which do not all assume the same form 
(32.),—to determine if the several known forms belonging to 
the group do not also belong or may not be assumed by each 
member of the group. (32.) 
6. When two series of unlike physical properties (33.) are 
assumed by the same chemical substance, to observe if each 
series includes a different crystalline form. 
7. In the present state of the doctrine of isomorphism it is 
of importance to collect and tabulate examples of like form in 
