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REVIEWS.

Geological Observation upon South America. By C. Darwin, M.A., F.R.S. 8vo. Smith and Elder.

THIS is another of Mr. Darwin's most important contributions to our knowledge of the physical geography of South America, and completes the geology of the voyage of the Beagle. The nature of the subject unsuits it for formal review in our columns, and precludes us from doing more than recommending it in the strongest possible way to the attention of our geological readers. They will find it a rich mine of facts. There is one point, however, to which in a practical view, attention should be here directed.

There exist in Patagonia and La Plata what are called Salinas, that is to say, salt-lakes, in which this substance is produced in vast abundance. But it is said to be found by experience too pure for the preservation of fresh meat, a circumstance that could hardly have been anticipated. Mr. Darwin was told by a merchant at Buenos Ayres that he considered the Plata salt 50 per cent less valuable than that of the Cape de Verds. If this inferiority be really owing to the purity of the former, as is supposed, it would be worth ascertaining whether the salt of La Plata could not be artificially brought up to the European standard. But the fact requires to be verified. Should any one desire to make the experiment, we would suggest the expediency of submitting a sample to some experienced analytical chemist, who might, perhaps, suggest the means of reducing the purity to the standard of European salt, if it really requires to be so reduced.

The merchants interested in this trade are, however, best able to judge whether it would answer their purpose to incur such a charge.