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POPULAR SCIENCE REVIEW. 
cent, of carbonic acid, the remaining 0*43 per cent, being oxygen. In a 
subsequent experiment, 31*07 per cent, of the gas was carbonic acid and 
68*93 per cent, nitrogen. The author believes that the carbonic acid comes 
from a fermentation within the fruit, the ferment being produced at the 
time of ripening. 
Action of Light on Iodide and Bromide of Silver. — Mr. Carey Lee, who is 
one of our best authorities on this subject, has contributed an important 
article to “ Silliman’s American Journal ” (April 1875). In this he has 
given the results of 160 experiments. The results, with such slight and 
altogether unimportant variations as necessarily arise from slight differences 
of preparation and differences in the character of the sun’s light, were 
remarkably concordant, and may be summed up as follows : — 
1. AgBrI and Ag are sensitive to all the visible rays of the spectrum. 
2. Agl is more sensitive than AgBr to all the less refrangible rays and 
also to white light. 
3. The sensitiveness of AgBr to the green rays was materially increased 
by the presence of free silver nitrate. 
4. AgBr and Agl together are more sensitive to both the green and the 
red rays (and probably to all rays) than either Agl or AgBr separately. 
5. There do not exist any rays with a special exciting or a special con- 
tinuing power, but all the coloured rays are capable both of commencing and 
continuing the impression on silver iodide and bromide. 
GEOLOGY AND PALAEONTOLOGY. 
The Evolution of the Crocodilia and on Stagonolepis Robertsoni. — One of the 
most important papers that have for some years been read before the Geo- 
logical Society was that of Professor Huxley on the above subject (April 
28, 1875). After referring to his paper read before the Society in 1858, the 
author stated that he had since obtained, through the Rev. Dr. Gordon of 
Birnie, and Mr. Grant of Lossiemouth, further materials, which served at 
once to confirm the opinion then expressed by him, and to complete our 
knowledge of Stagonolepis. The remains hitherto procured consist of the 
dermal scutes, vertebrae of the cervical, thoracic, lumbar, sacral, and 
caudal regions, ribs, part of the skull and the teeth, the scapula, coracoid 
and interclavicle, the humerus, and probably the radius, the ilium, ischium, 
and pubis, the femur, and probably the tibia, and two metacarpal or meta- 
tarsal bones. The remains procured confirm the determinations given by 
the author in his former paper, except that the mandible with long curved 
teeth, therein supposititiously referred to Stagonolepis , proves not to belong 
to that animal. The crocodilia were divided by the author into three 
groups. The paper is of much interest. 
Boring Mollusca in the Oolitic Rocks. — In the u Agricultural Student’s 
Gazette ” (April), a journal published at Cirencester, Professor J. Morri’s has 
an excellent paper on the above subject, of which we can only give a part. 
The rocks examined were those of a quarry situated near the canal on 
the farm land of Mr. Sargeant, which has been long worked for road stone 
