4.21 : 6.72, or ------------ = 52 per cent.
72

Mr. B.D. Healey, Assoc. M. Inst. C.E., and the author are just now
constructing large experimental plant in which water gas will be used as
the reducing agent. This plant would have been at work before this but
for some defects in the valvular arrangements, which will be entirely
removed in the new modifications of the plant.

* * * * *

ANTISEPTIC MOUTH WASH.

Where an antiseptic mouth wash is needed, Mr. Sewill prescribes the use
of perchloride of mercury in the following form: One grain of the
perchloride and 1 grain of chloride of ammonium to be dissolved in 1 oz.
of eau de Cologne or tincture of lemons, and a teaspoonful of the
solution to be mixed with two-thirds of a wineglassful of water, making
a proportion of about 1 of perchloride in 5,000 parts.--_Chemist and
Druggist_.

* * * * *

ANNATTO.

[Footnote: Read at an evening meeting of the North British Branch of the
Pharmaceutical Society, January 21.]

By WILLIAM LAWSON.

The subject which I have the honor to bring shortly before your notice
this evening is one that formed the basis of some instructive remarks by
Dr. Redwood in November, 1855, and also of a paper by Dr. Hassall, read
before the Society in London in January, 1856, which latter gave rise to
an animated discussion. The work detailed below was well in hand when
Mr. MacEwan drew my attention to these and kindly supplied me with the
volume containing reports of them. Unfortunately, they deal principally
with the adulterations, while I was more particularly desirous to learn
the composition in a general way, and especially the percentage of
coloring resin, the important constituent in commercial annatto. Within
the last few years it was one of the articles in considerable demand in
this part of the country; now it is seldom inquired for. This,
certainly, is not because butter coloring has ceased to be employed, and
hence the reason for regretting that the percentage of resin was not
dealt with in the articles referred to, so that a comparison could have
been made between the commercial annatto of that period and that which
exists now. In case some may not be in possession of literature bearing
on it--which, by the way, is very meager--it may not be out of place to
quote some short details as to its source, the processes for obtaining
it, the