546 
FOURTH BULLETIN OF 
[1846. 
of three inches. This stately species appears different in habit from the small 
species growing in the United States, where they only reach the height of a foot. 
There is also a large tree found in the swamps, belonging to the order Anacar- 
diaceae, and bears a large fruit, similar to the mango, but not edible. 
The province of Sambas is said to be very salubrious, not only with regard to the 
natives, but also Europeans. This would not be the conclusion arrived at from an 
inspection of the country, which consists of extensive marshes principally, and a 
tew rounded hills, which occur irregularly unconnected with a mountain chain. 
In the small Malayan village before mentioned the soil was a black marl, and 
apparently overflowed at times, and when stirred up to the depth of a foot, emitted 
an almost insupportable stench, probably of sulphuretted hydrogen gas. This 
condition appears irreconcilable with its salubrity. Dr. Ferguson has written a 
treatise on the history and nature of marsh poison, (much referred to,) the result 
of his investigations in Holland, Spain, Portugal, and the West Indies. He tries to 
prove the fact that the driest situations are very frequently, contrary to expecta¬ 
tion, the most unhealthy. 
In his remarks he says, “ one only condition seems indispensable to the produc¬ 
tion of marsh poison on all surfaces capable of absorption, and that is the paucity 
of water, where it has recently abounded. To this there is no exception in cli¬ 
mates of high temperature, and from which we may justly infer that the poison is 
produced at a highly advanced stage of the drying process.” 
In another place Dr. Ferguson says, “it is from these, (the dried and half 
dried margins of lakes and marshes,) that the poison uniformly emanates, and never 
from the body of the lake or pond ; and I think it may be fairly presumed, that 
water as long as it can preserve its particles above the surface is innoxious, and 
that it must first be absorbed into the soil, and disappear before the eye, before it 
can produce any mischievous effects. Whoever in malarious countries waits for 
the evidence of putrefaction, will, in all the most dangerous places, wait too long; 
as every one can testify, who has seen pestilence teem forth to the paralyzation of 
armies, from the bare barren sands of the Alentogo in Portugal, the arid burnt 
plains of the Estremadura in Spain, and the recently flooded table lands ofBarba- 
does.” 
Baron Humboldt, speaking of the intermittents which are so common near the 
great cataracts of the river Orinoko, says, “ the causes are violent heats, joined 
with the excessive humidity of the air, bad nutriment, and, if we may believe the 
natives, (as well as the missionaries,) the pestilent exhalations that arise from the 
bare rocks of the cataracts.” Many persons are spoken of, who, having passed the 
night on the black and naked rock, have awakened in the morning with a strong 
paroxysm of fever. Humboldt thinks that this is caused by the high tempera¬ 
ture of the rocks, in consequence of their being coated over with a layer of the 
oxide of manganese and iron. The higher temperature of these rocks is a very 
doubtful cause ; but there is a relation between this fact and those mentioned by 
Dr. Ferguson, of which the desiccation of nearly bare rocks in Spain, and of a 
very thin bed of earth overlaying coral rocks in the West-Indies, has given rise to 
the most pestiferous exhalation. 
I may also mention a fact corroborating Baron Humboldt’s observations at the 
cataracts. Singapore is celebrated for its salubrity, although having several marshes 
extending into the town and the immediate neighborhood ; and I was informed by Dr. 
Oxly, surgeon of the honorable East India Company, that but one case of malig¬ 
nant fever had occurred to his knowledge since the place has been in the posses¬ 
sion of the English, since 1819. 
But an island in the harbor, called “Blatten Matte,” about two and a half miles 
distant from the town of Singapore, is notorious for being unhealthy. This island 
I took occasion to visit in a Malay boat, and when passing one end where the 
rocks were exposed, I requested one to step out and break me off a portion ; but 
they all declined, saying that the people always took sick who went upon those 
rocks, but were willing to pull a quarter of a mile farther, where they said they 
could obtain some on the island. These rocks are composed of a coarse sandstone, 
containing much oxide of iron, and coated with black oxide of manganese. I am 
induced to believe the opinions of these ignorant people correct, for they have no 
doubt been obtained from experience, for they are much accustomed to fishing 
about these islands, and visiting them for the purpose of obtaining pine-apples. 
