Besides, each mass of mercury, would
exert some attraction on the weight on the other side, and thus lessen
the deviation of the balance.
The method given by Prof. Mayer, except for the suggested employment of
mercury, is then no improvement on ours. If we should use mercury, we
would construct a cubical vessel to contain it, and use it as we propose
to use the lead block. The advantage of using mercury is, however,
counterbalanced by the difficulty of obtaining it in such large
quantities as would be necessary.
ARTHUR KONIG.
FRANZ RICHARZ.
Berlin, Physical Institute of the University, March 15.
* * * * *
PHYSICS WITHOUT APPARATUS.
_The Porosity and Permeability of Bodies._--Take two tumblers of the same
size, place one of them upon a table, and pour into it a small quantity
of nearly boiling water. Cover this glass with a sheet of cardboard, and
invert the other one upon it. This second tumbler must be previously
wiped so as to have it perfectly dry and transparent. In a few seconds
the steam from the lower tumbler will traverse the cardboard (which will
thus exhibit its permeability), and will gradually fill the upper
tumbler, and condense and run down its sides.
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