BATH CHEMISTS’ ASSOCIATION. 
570 
Pills should be kept as small in size as practicable. In order to this, some of the soft 
extracts in general use might be kept dried down ready for making up, or in the case 
of those seldom required, by evaporating them on a small pill tile in front of an ordinary 
fire. Ehubarb should be made up with some thin liquid, and as much added at once as 
will be sufficient to make up the mass. Quinine pills may be kept down in size by 
reducing the quinine to a fine powder before attempting to make up. 
Some substances are very difficult to incorporate. The sulphates of zinc and iron 
should first be reduced to fine powder, and confection of hips (that sheet-anchor of the 
pill-maker) be used to bind them into a mass. Creasote and essential oils are rather 
troublesome things to get into pill-masses when ordered in large quantities; some re¬ 
commend their being absorbed by any powder ordered along with them, or added expressly 
for the purpose; others, that they should be added last; and others, that they should 
be made into a mucilage with a few drops of strong solution of gum, prior to being ab¬ 
sorbed by the powders. Oxide of silver should be compounded with non-saccharine 
substances, to prevent deoxidation. Many pill-masses, as the compound galbanum, 
yield readily to a warm pestle and mortar, when all other treatment fails. The objec¬ 
tionable smell and flavour of valerianate of zinc and other offensive medicines, may be 
almost entirely covered by a skilful coating of silver leaf or of balsam-tolu. 
The next class of preparations—ointments—will not require many comments. They 
should be made uniform, both in consistency and colour, and every trace of grittiness 
avoided by rubbing down insoluble substances with oil, or dissolving in hot water such 
as are soluble, as in the case of iodide of potassium and tartar emetic. A metal knife 
should not be used for ointments containing nitrate of mercury, corrosive sublimate, 
iodine, or even red precipitate, if the ointment be melted or the knife have to come in 
contact with the precipitate prior to its being thoroughly mixed in the ointment. 
The last preparations to be touched upon are plasters, as regards the manipulation of 
which more may be learned by one month’s practice than by twelve months’ lecturing. 
Perhaps the stiff “ paper form” may be suggested, as affording a great improvement upon 
the old system of spreading plasters without one. Also that opium, belladonna, and 
ammoniacum plasters should have an adhesive margin. 
A discussion followed the reading of the paper, and the meeting offered its best thanks 
to the author. 
This being the concluding meeting of the session, the Association adjourned until 
October. 
BATH CHEMISTS’ ASSOCIATION. 
At the April meeting of the Society, held at the Commercial Booms on Friday the 
7th, the President in the chair, Mr. W. W. Stoddart, of Bristol, read a paper on “The 
Nature and Properties of Heat practically applied.” In introducing his subject, the 
author remarked the great changes that had taken place during the last few years in the 
study of thermotics, and showed that the phenomena of heat were only those arising 
from the same, force that, under other circumstances, gave rise to electricity, magnetism, 
and light. The author then briefly sketched the history relative to the atomic doctrine 
and the dynamical theory of heat, as propounded by Messrs. Joule and Grove, Professors 
Tyndall, Clausius, Helmholtz, and many others. After giving the characters of atoms, 
as at present received, and their laws of combination, which were illustrated by ex¬ 
amples, the interstitial ether was then described, and the analogies that exist between 
heat and sound pointed out. 
The experiments illustrating the paper were made by using the thermopile and gal¬ 
vanometer instead of thermometers. It was shown that whenever a metallic body was 
unequally heated, an electric current was induced, the heated end being positive while 
the cooler one was negative. The author then proceeded to show that when two bodies, 
heterogeneous in their nature, as flannel and glass, were rubbed or struck together, elec¬ 
tricity was developed; but when their natures were homogeneous, then heat was de¬ 
veloped. Another difference between the effects of heat and electricity is, that while 
the former usually lessen atomic affinity, causing bodies to expand, the latter increases 
it, causing contraction. 
A very beautiful instrument was exhibited, which, by means of a combination of 
