INEUSUM GENTIANS COMPOSITUM. 
conductors M light and heat are the worst of electricity. For example, a diamond so 
beautifully transparent absolutely stops an electric current, -while a piece of black char¬ 
coal, an equally pure carbon, but opaque to every ray of light, is an excellent conductor 
of electricity. Metals, however, behave differently, and differ among themselves, for a 
good metallic conductor of electricity is an equally good one of heat. Silver conducts 
heat sixteen times better than German silver, and fifty times better than bismuth. 
A curious, and apparently paradoxical experiment was shown : on one of the metallic 
cubes, filled with hot water, was placed a small cube of bismuth, and one the same size 
of iron. On each of these was placed a small piece of wax, when it was found that the 
wax melted first on the bismuth, although the iron is the better conductor. This ap¬ 
parent contradiction was shown to be owing to the difference in their specific heats, 
that of iron being 1T38, while bismuth is only ‘308,—the iron requiring three times the 
amount of heat more than the bismuth before it could part with sufficient to melt the 
Max. It is therefore a matter of some importance in pharmacy as to the materials used 
for apparatus. A glass or porcelain vessel requires a great deal more heat to boil water 
than one of copper or iron. Indeed, it is a fact that water is hotter in a glass vessel just 
before ebullition begins than in a metallic one. Boiling goes on far more rapidly and 
equally in a metallic than in a porcelain vessel. A dry atmosphere is perfectly diather- 
manous, and permits all the rays of light and heat to pass, -while water bars their 
progress. 
The paper was concluded by explaining the beneficial effects of mists and dews in 
modifying and equally distributing the heat-rays of the sun. The whole was illustrated 
by a series of illustrative experiments and very delicate instruments. 
The President expressed the obligation he felt to Mr. Stoddart for his kindness in 
coming to Bath. A cordial vote of thanks for the able paper, and the interesting manner 
in which Mr. Stoddart had treated the subject, was proposed by Mr. Merriken, and carried 
by acclamation. 
ORIGINAL AND EXTRACTED ARTICLES. 
INFUSUM GENTIANS COMPOSITUM, P.B. 
BY A. F. HASELDEN. 
Whilst the British Pharmacopoeia is still under revision, no apology I trust is 
necessary for bringing again into notice this much-maligned preparation 
probably it would be more proper to say by some much-abused infusion • foi\ 
after all, it would seem that the objection to it rests mainly upon a difference 
of opinion, as to whether the flavour of lemon or coriander is to be preferred, 
as there are to be found staunch admirers of both ; but I labour under the im¬ 
pression that none take exception to the process, at least I have not yet met 
with any who complained upon that score. I have more than once prepared infu¬ 
sions according to the P.B. process, employing the ingredients, in the one case 
of the British Pharmacopoeia, and, in the other, those of the London • and 
having kept both for six or seven months under the same conditions, can speak 
favourably alike of them as to their remaining good and fit for use. When first 
made, the lemon flavour, or, as I have heard it defined, the punch-like odour of 
the London infusion, to my taste is decidedly preferable to the coriander of the 
British ; but I am bound to say, that by keeping, some of the freshness of the 
lemon disappears. Still even then, taking it per se, I prefer it; but when mixed 
with other substances in draughts or mixtures, the difference between the two 
is in many instances scarcely, if at all, perceptible. Possibly the admirers of 
coriander would be satisfied with the retention of the process, whilst lemon was 
substituted for the pet carminative fruit 5 seeing that it plays a prominent part 
in several other preparations, it might the more readily be resigned in this 
Having once more opened the question of infusions, I cannot resist the 
