properties of the viperine venom,
particularly by venturing to _taste_ it; at the same time he has
likewise contradicted some of those he had formerly made, whereby he
had been induced to believe, this poison partook of a degree of
acidity: for instance, he formerly asserted that he had seen this
sanies, "as an acid, turn the blue tincture of _heliotropium_, to a
red colour;[8]" whereas his more modern trials convinced him, it
produced no alteration at all.

[8] Second edition of those essays, page 10.

The essays on the _tarantula_ and _mad dog_, are likewise considerably
enlarged in the last impression; especially the latter, in which is
now comprehended a regular and elegant history of the symptoms
attending the bite of this enraged animal, the reason of the
consequent _hydrophobia_, and more extensive directions for the cure:
also an accurate description of the _lichen cinereus terrestris_, its
efficacy, and manner of acting. A composition of equal parts of this
plant and black pepper, was inserted, at our author's desire, into the
London dispensatory, in the year 1721, under the title of _pulvis
antilyssus_, which he afterwards altered by using two parts of the
former, and only one of the latter, as it now stands: in 1735 he also
recommended the use of this medicine in a loose sheet, intitled, _a
certain cure for the bite of a mad dog_.

In treating of poisonous minerals, exclusive of what is added
concerning mercurial unctions, our author has given a new analysis of
the antient and modern _arsenic_; and his essay on deliterious plants,
has afforded him an opportunity of enquiring into the _cicuta_, so
much in use of old for killing, especially at Athens, and which is
said to have been administered to _Socrates_ in consequence of his
condemnation. To this he has likewise subjoin'd an appendix,
concerning the mischievous effects of the simple water distilled from
the _lauro-cerasus_, or common laurel, which were first observed some
years since in _Ireland_, where, for the sake of its flavour, it was
frequently mixed with brandy.--His observations upon venemous
exhalations, are not less extended, nor ought the, as well useful as
ornamental, plates added to this last edition, to pass unnoticed,
particularly, "The anatomical description of the parts in a viper,
and in a rattlesnake, which are concerned in their poison," by our
great anatomist the learned and ingenious Dr. Nichols.

In 1703 Dr. _Mead_ communic