The next experiment was made by substituting a piece of the skin (freed
from chlorine by washing) of a freshly killed sheep for the bladder. The
ointment in No. 3 in this case was made with 10 per cent. of lard. No
reaction was obtained, at the ordinary temperature, after twelve hours,
nor after eight more hours, at a temperature of 25-30 deg. C. After letting
them stand for eight hours longer at 30-37 deg. C., a faint reaction was
obtained in the case of the ointment made with unguentum paraffini; a
still fainter with No. 3; but no reaction at all with No. 1 (that made
with lard). None of the fats passed through by osmosis. After eight
hours more, the iodine reaction was quite decisive in all cases, but no
fat had passed through even now. On titrating 20 grammes of the contents
of each beaker,
No. 1 required 0.5 c.c. of silver solution.
No. 3 " 0.5 c.c. "
No. 2 " 0.7 c.c. "
showing that the most iodine had osmosed in the case of the ointment
made with unguentum paraffini (equivalent to vaseline).
* * * * *
THE TAILS OF COMETS.
I.--If we throw a stone into the water, a wave will be produced that
will extend in a circle. The size of this wave and the velocity with
which it extends depend upon the size of the stone, that is to say, upon
the intensity of the mechanical action that created it.
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