256 EVOLUTION OF SULPHURETTED HYDROGEN. 
case of sulphuretted hydrogen, zinc and not iron must be 
employed. Mr. Daniell regretted that Davy's zinc-protec- 
tors had been so soon abandoned, and only because the cop- 
per, not acted upon by the muriatic acid, became a nucleus 
for earthy, vegetable, and animal matter, and the ship's bot- 
tom was in consequence fouled, as it is termed. The remedy 
for this, he said, was most simple. Let the protectors be so 
arranged that contact may be broken and renewed at will. 
The zincs and copper separated for a short time, the earth 
deposits would soon be removed. In consequence of Mr. 
Daniell's report to the Admiralty, chlorine has been furnish- 
ed the Niger Expedition, and no ship hereafter will proceed 
to the African station without that purifier in store, nor with- 
out zinc-protectors for her copper. It is to be hoped that all 
ship-owners will follow the example of the Admiralty Board 
in this respect. — Literary Gazette, No. 1272. 
•Additional evidence oj the active agency of Salt Water • 
when in contact with decaying Vegetable Matter, in 
generating Miasma, in a hot climate, contained in a let- 
ter from Professor Daniell to the Editor of" The Friend 
of Jlfrica." 
Mr Dear Sir, — The evidence of the worst cases of mala- 
ria being connected with the decomposition of the sulphates 
in sea-water increases upon me every day, and I have now 
the pleasure to send you an abstract of a paper, which you 
will find at length in the 29th volume of the Annales de Chi- 
mie, p. 225, by Signor Gaetano Giorgini, which offers the 
strongest possible confirmation of my opinion. I trust that 
it may tend to give confidence to the African expedition ; for 
if we rightly know the cause of the pestiferous exhalations 
upon the coast, the prevention of ill eflects is obvious and 
eaS y : — Steam through the salt-waters as fast as possible, and 
while obliged to be on them make a plentiful use of chlorine 
fumigation, which instantly decomposes the sulphuretted hy- 
drogen. — I am, &c. 
J. F. Daniell. 
Captain Washington, R. N. 
