LEEDS CHEMISTS’ ASSOCIATION. 
5 GO 
master or another assistant; that of having the measuring of all powerful remedies, as 
tr. aconiti, tr. nucis vomic., preparations of hydrarg. oxymur., etc., when ordered for in¬ 
ternal administration, witnessed. There is further, the now generally adopted arrange¬ 
ment of a chemist’s shop, so that the dispensing of medicines is kept quite apart from 
the retail counter. In shops where the stock-bottles are exclusively stoppered, a tin 
cap fitting loosely over the stopper would probably form a sufficiently distinctive feature 
to distinguish poison-bottles from ordinary ones; or if caps be the covers for many of 
the ordinary bottles, then a different-shaped one might be used for the poisons. Still 
these are but aids, and the great security against accident lies in the concentrated atten¬ 
tion of the dispenser. Quickness of perception, or a readiness to understand the general 
interpretation of a prescription ; coolness, or a collectedness of mind under a heavy 
pressure of work, are also qualifications worth the cultivating. 
Under the second head it may be just remarked at the outset, that a quick eye and 
delicate nose are both useful as checks and tests. Medicines, as generally prescribed in 
this country, may be classed under one of the following divisions :—liquids, comprising 
mixtures, lotions, liniments, gargles, etc.; pills and powders ; ointments and plasters. 
The first class will demand the largest share of attention. In compounding medicines, 
avoid using a mortar as much as possible, thereby preventing unnecessary trouble and 
straining, as liquids very rarely come out of a mortar in the same condition as they 
entered it. Many of the soluble salts, such as bicarbonate of potash, bicarbonate of soda, 
Rochelle salts, etc. (if of the best make) are perfectly and readily soluble in ordinary 
aqueous vehicles, yet how r common the practice of rubbing them dowm in mortars, 
thereby running the risk of contaminating them, besides losing time. The heavy car¬ 
bonate of magnesia and trisnitrate of bismuth may also, as a rule, be slipped into the 
bottle, without the necessity of dirtying a mortar. All soluble scaly preparations dis¬ 
solve more readily in the bottle than by rubbing in a mortar. On the other hand, there 
are many cases in which the use of the mortar is absolutely necessary to the production 
of an elegant mixture ; as when bulky powders are prescribed, which must be gradually 
rubbed up with the liquid ; also when considerable effervescence takes place in mixing; 
when hot water is required for solution; when crystals are to be broken down and dis¬ 
solved, or rubbed up when insoluble. When extracts are ordered in mixtures, the 
readiest means of dissolving them is by working them into a smooth liquid paste on a 
slab with a palette knife, and then scraping off into a measure containing more of the 
vehicle, and gently mixing with the knife. Oil of almonds and olive oil, when ordered 
with liquor potassse, form a very nice emulsion, by diluting the alkali freely, and shaking 
the two together. When compounding a mixture containing ingredients which act 
chemically upon each other, it is advisable to keep them as far apart, and as much 
diluted, as possible. Chloroform, creasote, and essential oils, should, if any tinctures 
are present, be dissolved in them prior to being added to the mixture. In rubbing oil 
of cubebs or other essential oils in large quantities -with mucilage, great care is necessary 
to avoid an insoluble compound forming: this may be prevented by judicious diluting 
during the process. Gallic acid should be dissolved in hot water, as also should quinine, 
if there be no other solvent present; but care must be taken to ascertain that there is 
not more of either than the mixture will afterwards retain when cold. Tincture of ben¬ 
zoin, tolu, and other gum-resin tinctures, should be added to mixtures nearly at the last, 
and immediately shaken gently. Hydrocyanic acid should be added last of all. Nitrate 
of silver, diacetate of lead, and other salts decomposed by ordinary water, should be dis¬ 
solved in distilled water. 
The following queries may here be put:—What does a medical man intend when he 
expresses the quantity of any powerful medicine in a mixture by the term guttas ? 
Does he really mean drops, or is he under the impression that the difference between 
drops and minims is so trivial as not to necessitate his particularizing? When the 
term “ ad Octarius” occurs, which is intended, a sixteen or twenty ounce mixture ? Is 
it generally understood that unless the prescriber specifies P.B. he means P. L. ? 
The next class to be noticed, are pills and powders. With respect to the latter,The 
best mode of obtaining a uniform admixture, perhaps, is, by weighing and rubbing 
well together the smaller quantities first, and then adding the larger ones gradually ; 
and in cases where large quantities of bulky powders are ordered, by sifting. As to 
their division into separate doses, probably a practised eye may be more safely trusted 
than many a pair of dispenser’s scales. 
VOL. VII. 2 p 
