486 
ON THE MEDICAL TOPOGRAPHY OF SINGAPORE. 
and that what was detached in the specimens sent to England, ori¬ 
ginated in the bottles themselves from decomposition of their con¬ 
tents.” 
Professor Gardiner of the Hampden Sidney College, endeavours 
to shew that Sulphuretted hydrogen is the active agent in the pro¬ 
duction of fever of malarious districts, both maritime and inland. 
His arguments are principally founded on Professor DanielPs theory, 
which has been found to be incorrect, and on suspending polished 
silver to the action of what gas might be, in 3 small rivers, in mar¬ 
shes, small springs and the air over marshes and springs ; in all these 
experiments the silver was stained, in marshes in 24 hours, in rivers 
a month, and in the air sometimes longer. The effect produced on 
the silver was so slight and embraced such a length of time to pro¬ 
duce the effect, that these experiments of Professor Gardiner cannot 
be considered of any weight. In opposition to his theory I would cite 
this, that in a part of Paris where the contents of the necessaries of 
that vast city are collected for making poudrette, sulphuretted hy¬ 
drogen is disengaged in large quantities, to the olfactory annoyance 
of the neighbourhood, but, according to the French commissioners 
who examined the spot, not to the visible detriment of the health of 
the neighbourhood or workmen in the buildings. Sometime ago 
I made the following experiments. I saturated white blotting paper 
in a solution of carbonate of lead, and then dried it; this I cut 
into pieces and suspended in various parts of the to wn of Singapore, 
near the Jail, in the river, and in the canal in new bridge road, and 
in the course of a few hours all were visibly blackened; that in the 
canal near the Jail being the first to be so, then the canal on new 
bridge road, the last to be so being that which was suspended in the 
river, but all shewing that sulphuretted hydrogen existed to a great 
extent. 
About the same time I suspended in the air in several situations 
over the marsh at Siglap, where I have mentioned fever once a- 
bounded, several pieces of paper saturated with lead, and in 48 
hours exposure no visible effect was produced, shewing that no sul¬ 
phuretted hydrogen existed. This plan of testing sulphuretted 
