The Sun.
London, England, 1854-09-26 00:00:00

TRH MEDICINAL MIMI ♦ND ITS REPRODUCTION.

Mr. RICHARDSON offered some remarks in this section
" On the Medicinal Leech, and its Method of Reproduc-
tion." Mr. Richardson said that only two works had
been written relative to the mode in which the leech was
reproduced, and in both the facts had not been cor•
rectly stated. The egg of the leech was peculiar, and
dissimilar to anything known in physiology. The egg
appeared as large as the leech itself. The ovum was
first surrounded with viscous matter, and then with a
vegetable substance, giving it the appearance of a silk-
worm's cocoon. From this strange egg the young
leeches issued in the form of threads ; but it was not
necessary that the parent mother should assist at their ,
incubation. Ile himself had hatched some dozens of
leeches without the aid of the parent leech, by merely i
followingse the neesery laws of nature. The leeches,

with the cocoons, were exhibited, and excited much
interest.

A PARTIAL CASE OF ALBINOISMUS.
Dr. iti3IAN gave an account of a partial case of
albinoismus which he had met with in one of tlle Liver-
pool hospitals ; a black man, whose hands were covered
with white spots, and whose legs had become as white as
those of a white man. Ile was a native of Antigua,
where his grandfather was a white man. While in China,
about 18 months ago, he was sadly afflicted with
i
rheumatism, and treated, as tis supposed, with mercury.
Soon after, the white spots began to appear, first on his
right hand and then on his left, gradually extending over
his legs and arms; white spots also came upon his face in
the cold weather, but in the surnmerseasou they became
covered with a darker skin, which disappeared as the
heat of the weather moderated. The man asked him (Dr.
Inman) if he could not effectually blacken his skin again.
Dr. Inman recommended walnut juice, and on being in-
formed that it would dye his skin at least a deep brown,
he appeared much pleased. All these spots were quite
free from disease, but more easily injured than the dark
skin.

Dr. CARPENTER said the case was by no means an un-
precedented one. In America a genuine negro turned
completely white, preserving as the only peculiarities of
his origin the woolly hair and features of his race.

SECTION G.-MECHANICAL SCIENCES.
BOILER EXPLOSIONS.

The PRESIDENT read a paper by Mr. J. Sewell, " On
Boiler Explosions." Mr. Sewell's opinion as to their
cause differed materially from that hitherto held, which
was, that they were caused by excessive pressure. Mr.
Sewell, though he admitted that this has a great deal to
do with explosions, believed that the moment the elastic
force of the steam became greater than the resisting
power of the boiler, the water and steam escaped, and
the water, bursting into steam, became a perfectly elas-
tic force. Mr. Sewell drew attention to the general con-
struction of boilers, and the injury which was done by
the present process of punching. He proposed also to
strengthen the plates in that part by rolling them thick
along the edges.
Mr. CLAY observed that shortness of water was the
most general cause of explosion; and another cause was
defects in parts of the boiler. He drew attention also to
certain samples of iron on the table, upon which he had
experimented.
Mr. N&SMYTH had himself described the same results
before the Association in 1843 ; it was an excellent me-
thod, and anchors were now thus annealed by the Admi-
ralty. Referring to boiler explosions, he deprecated the
practice of attributing them to mysterious causes, such
as the evolution of gases, &c. To do this was more dan•
gerous than the boiler explosions themselves, inasmuch
as it diverted attention from the plain and simple cause ;
namely, in too many cases, the parsimony of employers.
If a law were passed to compel proprietors to have their
counting-houses either over, or immediately adjoining
the boilers, doubtless these accidents would be much re-
duced in number.