SCIENTIFIC SUMMARY. 
529 
These two effects proceed directly, the one being associated with 
the other, and the maximum for both being attained by a com- 
bination of three equivalents of water and one of hydrocyanic 
acid. 
2nd. That hydrocyanic acid possesses a powerful affinity for corrosive 
sublimate, which it retains without forming any definite com- 
pound. When the two are mixed together, the temperature 
becomes elevated, and the affinity is so powerful that it causes 
the conversion of the protochloride into the perchloride, and pro- 
duces metallic mercury ; this effect, however, only takes place in 
the presence of water. 
3rd. Other salts act on the acid in the same way, but to a far less 
extent ; but the greater number act by increasing the tension of 
the vapour. 
4th. In certain cases, the result of the action of the process of so- 
lution is to separate the hydrocyanic acid under the form of a 
subnatant stratum, although the quantity separated in this way 
has no relation to the affinity of the salt which was placed in the 
water.— Vide Comptes Rendus , lviii., 19. 
GEOLOGY AND PALAEONTOLOGY. 
Fossil Insects of the Carboniferous Formation in Illinois. — In Silliman’s 
American Journal , No. 109, we find a valuable paper by Mr. Dana, upon 
the insects of the latter formation. The species he describes and figures 
in the contribution referred to, is evidently one of the Neuroptera. In 
general form and the nervation of the wings, one of the species approaches 
the Semblids. From this fact, and also from the circumstance that the 
outer wings are so thin as to admit of the abdominal segments, and even 
the inferior wings being seen through, there is every reason to 
believe that the insect could not have been one of the Orthoptera. The 
anterior legs are peculiar in having a large and broad femur, armed above 
with very slender spines as long as the joint, three of which, though 
mutilated, are seen in the specimen. Mr. Dana supposes that these limbs 
were prehensile, as in the Mantis, and this idea is borne out by the fact 
that the tibia and tarsus are not in sight. Only the left leg in the specimen 
has the large joint tolerably perfect ; in the right, however, it is sufficiently 
distinct to show that it had the same large size, and was also spine-bearing. 
This fossil was discovered by Mr. J. Bronson, of the Miami University, 
and at his request it has received the generic title of Miamia , the specific 
one of Bronsoni having been appended by Mr. Dana. 
Exogenous Wood in Arenaceous Limestone. — Professor Haughton describes 
a curious specimen which he found in some of the beds of the yellow 
sandstone series of the north coast of Mayo, in Ireland. When a section of 
it was examined under the microscope (X 500 diameter), it presented the 
appearance of “ a bundle of rushes deprived of epidermis, containing 
elevated disk-like markings.” The rush-like appearance represented 
longitudinal tubes with areolse or warts on the interior surfaces of their 
