Page:Proceedings of the Royal Society of London Vol 1.djvu/450

Rh may be increased by artiﬁcial respiration, but never longer than for a few minutes. Its principal action is conceived to be upon the brain; but it appears to act upon the heart also. The stomach sometimes bears marks of inﬂammation; but the author has seen no instance of the intestines being inﬂamed.

The experiments of Mr. Brodie on corrosive sublimate, have led him to conclusions very different from the preceding respecting its mode of action. When applied to a wounded part, it produces a slough, without any aﬁection of the general system; and when taken internally, its eﬂ‘ects, he thinks. may be best explained by its local action on the stomach alone, unconnected with any absorption of it into the circulation.

When a solution of corrosive sublimate is taken into the stomach, the mucous membrane is found of a dull grey colour, having lost its texture, so as to be easily separated from the muscular coat; and as this precludes the idea of absorption into the circulation, Mr. Brodie conceives that its deleterious effects depend entirely upon its che- miwl action on the stomach, and that the brain and heart are thence aﬂ’ected by nervous sympathy.

The tendency of Dr. Herschel’s observations is to point out a difference between this second comet and the former, of which he lately gave an account to the Society.

The latter appeared to him as a nucleus about 5” in diameter, surrounded by a very faint chevelure. Since this appearance on the two ﬁrst days of observation was not well deﬁned, Dr. Herschel was in doubt whether to consider the nucleus as corresponding to the head of the former comet, or to the bright planetary body that he had observed in its centre ; being extremely small in comparison to the head, and as much too large to be supposed of a planetary construction. But on two subsequent days of observation, the nucleus was pretty well deﬁned, even with a power of 170 ; and the author was led to consider the latter as the more probable opinion. On the ﬁfth day of observation (which was the last time that it could be seen, by reason of the interference of the moon’s light), Dr. Herschel at-tended carefully to the magnitudes of the body, as it appeared to different magniﬁers; and by subsequent comparison on the following morning of objects of known diameter with his recollection of these magnitudes, he determined the measure of the nucleus to have been 5 '2744.

Since the distance of this comet from us was at that time rather greater than that of the sun, the real magnitude of the diameter thus measured is estimated at 2637 miles.

As the light of the chevelure was too feeble to be seen at this time, on account of the light of the moon, its greatest extent, in a direc-