55 
Ordinary Meeting, December 26th, 1866. 
Edward Schunck, Ph.D., F.R.S., President, in the Chair. 
Mr. Peter Hart exhibited a piece of lead pipe from the 
Ardwick Bridge Chemical Works, coated internally with 
oxide of manganese. The pipe was one inch in diameter, 
and the thickness of the coating of oxide of manganese was 
about a quarter of an inch. The oxide has not been minutely 
examined, but it consists no doubt largely if not wholly of 
the hydrated peroxide, as it evolves chlorine in quantity 
when gently heated with hydrochloric acid. The water 
used in the works is collected in tunnels cut in the red 
sandstone, and there is no doubt that the source of the man- 
ganese is the refuse chloride from the chlorine stills situated 
almost immediately over one of the tunnels. A portion of 
this chloride, having filtered through the sandstone, has 
come into contact with the bicarbonate of lime in the water, 
chloride of calcium and carbonate of manganese have resulted, 
which latter body, by after contact with oxygen, has become 
wholly or partially converted into peroxide. 
“ On some recent observations on the Specific Gravity of 
Sea Water,” by Thomas Heelis, F.R.A.S. 
The author had in the course of several long voyages 
accumulated a number of observations on this subject, all of 
which were made at sea with the hydrometer. On coming 
to examine and reduce his results, he had referred to a 
paper by the late Professor Forchhammer of Copen- 
hagen, published in the Philosophical Transactions. The 
Proceedings — Lit. & Phil. Society, — Yol. YI. — No. 7 — Session 1866-7 
