On Tropical Miasmata. ol 
neighbourhood of Naples, in different spots of Sicily, in the 
neighbourhood of sulphureous springs, &e. Now, do you know 
any account about diseases proper to such places? On the 
contrary, sulphureous springs are among the most distingui shed 
fountains of health. 
“] think, as to the exhalations of sulphuretted hydrogen, 
the same holds good as is said of carburetted hydrogen. It is 
also supposed that this gas, evolved from marshes, causes the 
intermittent fevers so common in their environs. Were this 
supposition. correct, what diseases ought the miners to suffer, 
who frequently work in an atmosphere containing above 'y of 
carburetted hydrogen ? 
“TJ believe that sulphuretted hydrogen may just as little 
take a share in causing diseases, as carburetted hydrogen does, 
though it is not to be denied, that a much smaller proportion 
of the former than of the latter is fatal to animal life. It is 
much more probable that the volatile vegetable matter ac- 
companying sulphuretted hydrogen, evolved from the water 
on the coast of Africa, originates diseases, as well as that 
which is mixed with carburetted hydrogen disengaged froim 
marshes. 
“ Professor Daniell remarks correctly, it is difficult to con- 
ceive how such a striking and important fact as the impreg- 
nation of the waters of the ocean, upon such a long line of 
coast, with sulphuretted hydrogen, could so long have escaped 
observation. It is true, he has turned, on this subject, to 
some of the accounts of the late travels in Africa, to seek for 
evidence, and communicated also some important observations 
made by Macgregor Laird. But in this account a horrid 
sickening stench peculiar to the miasma is only alluded to. 
It may still be supposed that this gentleman, when even un- 
acquainted with chemical properties, would have mentioned 
the similarity of that stench to that of putrefying eggs. An 
indescribable feeling of heaviness, languor, nausea, and dis- 
gust, with which one is oppressed in those swamps, is never 
experienced on breathing such quantities of sulphuretted hy- 
drogen as to fill a room with an unsupportable stench. 
“ Otherwise gases, when‘even heavier than atmospheric air, 
are very easily distributed through it, and thereby extremely 
