in the Waters of the Ocean. 1 7 



existence of the worst forms of malaria in places which we 

 now know combine all the necessary circumstances for the 

 generation of sulphuretted hydrogen. 



In Mr. Darwin's interesting Journal of the Voyage of the 

 Adventure and Beagle, he speaks of several such places, espe- 

 cially in Peru, in connexion with the well-known effects 

 of miasma, but not with any suspicion of the real origin of the 

 evil. He mentions repeatedly the efflorescence of the sul- 

 phates of magnesia and soda upon the soil, and that the mud 

 of the saline lakes is "black, and had a foetid odour." The 

 inhabitants suffer in such situations from the worst attacks of 

 ague. He remarks, p. 447, " The attacks of illness which 

 arise from miasma never fail to appear most mysterious. The 

 miasma is not always produced by a luxuriant vegetation with 

 an ardent climate ; for many parts of Brazil, even where there 

 are marshes and a rank vegetation, are much more healthy 

 than this sterile coast of Peru." 



" So difficult is it to judge from the aspect of a country 

 whether or not it is healthy, that if a person had been told to 

 choose within the tropics a situation appearing favourable for 

 health, very probably he would have named this coast." 



Its peculiarity consists in the saline efflorescence upon its 

 soil, of which the sulphates of magnesia and soda constitute a 

 very great proportion. 



May not the jungle fever in India depend for much of its 

 malignity upon the same cause? The soil in many parts 

 abounds not only with the nitrates of potassa and soda, but 

 the sulphates of soda and magnesia; these become washed 

 down by the periodical rains, and mingling with the decaying 

 leaves, the mutual reaction takes place. 



Is it not worthy again of the most exact inquiry, whether 

 the fevers which periodically afflict the cities of New York 

 and Charlestown, in America, may not be connected with the 

 mixture of animal and vegetable substances with the sea water 

 in their lower districts, where they usually originate; and 

 whether an attentive examination will not prove, that the same 

 impregnation of sulphuretted hydrogen, which we have esta- 

 blished upon the African coast, exists at the mouth of the vast 

 rivers of the American continent? Indeed I have been in- 

 formed by an officer high in the naval service, that during 

 the war instances of the rapid decay of ships' copper, similar 

 to that upon the African, were noticed upon the West-Indian 

 station . 



To bring the matter nearer home. Is it impossible that 

 the minor insalubrity of parts of our own coast, such as that 

 of Essex, may have some reference to the same causes acting 



Phil. Mag. S. 3. Vol . 1 9. No. 1 2 1 . July 1841. C 



