Handbook of the science and practice of medicine / by William Aitken.

  • William Aitken
Date:
1858
Catalogue details

Licence: Public Domain Mark

Credit: Handbook of the science and practice of medicine / by William Aitken. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

    151/880 (page 33)
    INFLUENCE OF SOIL IN PRODUCING MIASMATA. loxious miasmata, and consequently are a strong additional argument _n favour of the li}T)otliesis of vegetable decomposition generating she remote cause which produces some miasmatic diseases. It is certain, however, even when the conditions of heat, moisture, and vegetable matter most abound, that paludal diseases do not always assume their severest foi-ms : thus Jamaica is more unliealthy than Demerai-a, Demerara than Barbadoes ; and taking the West Indies ■generally, that country is more unhealthy than that of the East [ndies. There must be other cii-cumstances, therefore, affecting :he problem in question ; and there seems reason to believe that ;lifferences of geological formation, by favouring or otherwise iniiu- encing vegetable putrefaction, may variously affect the health of iiountries similarly situated in other respects. ! It is perfectly well known that different soils radiate heat vidth very different degrees of intensity, and consequently are, under the same cu-cumstances, of veiy different temperatures, having very dif- ferent powers of atti-acting moisture; and possibly also they may have other and more direct chemical affinities for generating or attracting the paludal miasm. Nothing, for instance, is better determined in husbandry than that the carbonate of Hme, mixed with the ordinary matters of a compost, gi-eatly forwards the pro- cesses of putrefaction, so that the mass thus prepared is fit in a nuch shorter time for the piu-poses of manui-e. The causes wliich jccasion this rapid decomposition have been investigated by Sir Eiunhprey Davy, and he has ascei-tained that lands situated in i'-alcareous districts, like the West Indies, where the surface is a ;pecies of marl a few inches deep, lying above limestone earth, are •!xtremely hot, and attract moisture largely. No springs, it is well •mown, arise on chalky hills, the water being unable to penetrate ;o impei-vioiis a soil; yet it is of common obseiwation that the ponds )n those hills are always full. The different powers of absorption of water by different soils is often well seen in this country ; for he sandstone and limestone hills of Derbyshii-e and of North Wales, or example, may be easily distinguished from each other at a con- idei-able distance by their different tints of verdure ; the grass on he sandstone hills being usually brown and burnt up, while that •n the limestone is flourishing and green. Now if the difference in ihe absorbing powers of different soils in this country is so strildng Vhen the atmosphere contains only 1-7.5th part of its weight of .-apour, how much greater results must arise from this difference of oil between the tropics, where the atmosphere contains three times hat quantity, or l-21st part of its own weight of va]K>ur. It ppears, therefore, there are some soils peculiariy favourable to the jecomposition of vegetable matters, and consequently to the more bundant extrication of marsh miasmata ; and it is remarkable that D