234 Scientific Intelligence. {[Marcs, 
ArTicLe VIII. 
SCLENTIFIC INTELLIGENCE; AND NOTICES OF SUBJECTS 
: CONNECTED WITH SCIENCE. 
I. Lectures. 
Mr. Clarke will commence his next Course of Lectures on 
Midwifery, and the Diseases of Women and Children, on Mon- 
day, March 18. The lectures are read every morning, from a 
quarter past ten to a quarter past eleven, for the convenience of 
students attending the hospitals, at No. 10, Saville-row. 
II. On taking Specific Gravities, and on the Cause of the Rupture 
of Leaden Pipes from Frost: in an Extract of a Letter from 
Dr. Redman Coxe, Professor of Chemistry, Philadelphia. 
It occurs to me, before I close my letter, to mention what I 
consider as a source of error in determining the specifie gravities of 
bodies; this is the employment of water as a standard at any other 
temperature than that at which this fluid is of a mean density, viz. 
at about 40°. If both above and below that point this fluid expands 
both by an increasing and diminished temperature, ought we not to 
fix upon that degree invariably for the purpose? for as we judge by 
comparative bulks of matter, a little variation may induce consider- 
able difference of result. Another circumstance arising from this 
anomaly in water expanding by cold below 40° is, that this is the 
chief cause of leaden pipes bursting, and not from the mere sudden 
expansion in its conversion into ice. My reason for believing this 
to be the case is, that we never see the leaden tube burst throughout 
the whole length, as should be the case if the solidification of the 
water was the cause; for as this is uniform throughout, so ought 
the effect to be: but it is chiefly in a small point, arising, as may 
be seen, from the gradual diminution of thickness in that part of 
the pipe, until becoming as thin as paper, it can no longer sustain 
the pressure of the fluid, and therefore yields. Hence only a few 
small openings are perceptible, not bigger than pins’ heads, which 
takes off the pressure by giving vent to the water. If this is the 
case, how can it be guarded against, excepting by increasing the 
thickness of the tube? - Now as the water goes into the pipe in a 
fluid state, it can scarcely become colder below the earth, removed 
as itis from the influence of the frost. This is a circumstance 
worthy of consideration in large cities where leaden pipes are em- 
ployed for the distribution of water. Did you ever hear of rats 
gnawing the leaden pipes to get to the water within? I have a 
large specimen of this kind. 
IIL. Chyle. 
Dr. Marcet has published a set of comparative experiments on 
the chyle from vegetable and animal food, in the sixth volume of 
