in the Waters of the Ocean, 1 3 



contact with air. This case is the more interesting, inas- 

 much as the gas never exists in sufficient proportion to be 

 discoverable by the usual tests ; nevertheless it acts in these 

 minute quantities with great energy. 



But now a much more important and interesting question 

 than that of the preservation of the copper sheathing of ships 

 forces itself upon our attention, and that is, whether the ex- 

 istence of this deleterious gas in the atmosphere, which must 

 necessarily accompany its solution in the waters, may not be 

 connected with that awful miasma which has hitherto proved 

 so fatal to the explorers and settlers of the deadly shores of 

 Africa ; and whether, if so, science may not suggest something 

 to palliate an evil which is so dreadfully opposed to the pro- 

 gress of civilization in those parts. 



When this matter was first brought under my considera- 

 tion, I was surprised that the nauseous smell which must 

 necessarily be evolved from water impregnated with this gas, 

 at so high a temperature as that of the equinoctial regions, 

 had not been noticed. I have in consequence turned to some 

 of the accounts of the late travels in Africa, to seek for evi- 

 dence upon the subject; and in the narrative of an expedition 

 into the interior of Africa, by the river Niger, by Macgregor 

 Laird and R. A. B. Oldfield, I found the following important 

 observations: — 



" The principal predisposing causes of the awful mortality, 

 were in my opinion the sudden change from the open sea to 

 a. narrow and winding river, the want of the sea breeze, and 

 the prevalence of the deadly miasma, to which we were nightly 

 exposed from the surrounding swamps. The horrid sicken- 

 ing stench of this miasma must be experienced to be conceived : 

 no description of it can convey to the mind the wretched sen- 

 sation that is felt for some time before and after daybreak. 

 In those accursed swamps, one is oppressed not only bodily 

 but mentally with an indescribable feeling of heaviness, lan- 

 guor, nausea, and disgust, which requires a considerable effort 

 to shake off." 



Now, these observations were made in the very locality 

 from which some of the first waters which I examined were 

 taken, and nothing more is wanting to identify the cause of 

 the rapid decay of the ship's copper with that of the mortality 

 of the climate. 



It has been experimentally found, that so small a mixture 

 as a fifteen hundredth part of sulphuretted hydrogen in the 

 atmosphere, acts as a direct poison upon small animals, and 

 the sensations of languor and nausea, described by Mr. Laird, 

 are exactly those which have been experienced by persons 



