In a battery of 100 plates,
touching each other directly, and strongly pressed into a brass cylinder,
the portative force at each extremity rose to 30 grammes. This first
result having been obtained, I dismounted the batteries, plate by plate,
taking care to mark the upper and under side of each. I found then that
each plate retained only an excessively slight magnetism. Yet each of them
still constituted a flat magnet, of which the two faces are the polar
surfaces; for on rebuilding the battery it gave again a perfectly regular
magnet, though weaker than it was at first. The separation of the magnet
into its constituent plates, and its reconstruction, maybe repeated
indefinitely.--_Comptes Rendus._
* * * * *
Dr. T. Tommasi (_Cosmos les Mondes_) notes that the thermic constant of
thallium is exactly the mean of the thermic constants of potassium and
lead, the two metals which it most resembles in its chemical character.
* * * * *
IMPROVED GAS LIGHT BUOY.
[Illustration: GAS LIGHT BUOY.]
The accompanying engravings represent a light buoy made by the Pintsch's
Patent Lighting Company for the river Humber. The chief dimensions of the
buoy are given in the engraving, which also shows that the gas holder is
placed within the boat in such a way as to be protected from blows likely
to cause any leakage.
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