On Tropical Miasmata. 27 
other parts of the country,* while the latter immediately ar- 
rested our attention by its singular accordance with the ancient 
story, and is moreover peculiar in Palestine to the shores of 
the Dead Sea.+ 
On Tropical Miasmata. 
In the Friend of Africa, and also in this Journal, from 
that periodical, was inserted an analysis of the waters of the 
African coast, together with some remarks by Professor Daniell, 
on its bearing on the Niger Expedition. ‘“ We have now the 
gratification,’ says the editor of the Friend of Africa, “to add 
the following letter from Professor Gustav Bischof of Bonn, 
well known to the English reader by his Observations on Vol- 
canos in Professor Jameson’s Edinburgh Philosophical Journal, 
and who has heretofore shewn a lively interest in the welfare 
of the Niger Expedition.” 
‘‘Poppelsdorf, near Bonn, 20th April 1841. 
“My Dear Sir,—I am much obliged to you for sending 
The Friend of Africa. Deeply impressed with the vast im- 
portance of the expedition about to sail for the Niger, I in- 
stantly read over those valuable papers. The most interest- 
ing to me as a chemist, was the account of the sea-water on 
that coast, containing, in some instances, more than eleven 
cubic inches of sulphuretted hydrogen in a gallon. 
In support of the supposition of Professor Daniell, that the 
probability of a volcanic origin of the sulphuretted hydrogen 
is small, and that, on the contrary, its origin by the action of 
vegetable matter upon the saline contents of the water is ex- 
tremely probable, I venture to call your attention to some ex- 
periments I made twelve years ago, and published in the Jar- 
buch der Chemie und Physik, 1829, vol. iii., p. 80, and Neues 
Jarbuch der Chemie und Physik, 1832, vol. iv., p. 8377. These 
experiments being probably unknown to English philosophers, 
I take the liberty of communicating them briefly to you. 
* Hasselquist mentions it at Ras el Ain, near Tyre, p, 556. 
* Vide Robinson’s Biblical Researches in Palestine, yol. ii. p. 235. 
