90 
“ On the Degree of Accuracy displayed by Druggists in 
the Dispensing of Physicians’ Prescriptions in different 
towns throughout England and Scotland,”* by William 
Thomson, F.C.S. 
The results obtained by Mr. Allen, the public analyst for 
Sheffield, a short time ago in reference to the inaccuracies 
displayed by druggists in making up prescriptions, led me 
to believe that it would be interesting to have the same 
prescription dispensed by different druggists, in different 
parts of England and Scotland, and by analysis to decide 
the range of inaccuracies, if any. By the aid of my friend. 
Dr. Sinclair, of Manchester, to whom I am indebted for 
much subsequent help, I was furnished with two ordinary 
prescriptions, the principal ingredients of which admitted 
of very accurate determination, as I shall afterwards show. 
The prescriptions were as follows : — 
13^. Potass lodid 3ij 
Sp. Chlorof. 3j 
Aq. ad gvj 
M. |ss ter die. 
bL. Zinci Sulphat. 9 ij 
Aq- Pur gij 
M. Fiat Lotio. 
The processes of analysis were so simple for both that it 
leaves little doubt as to the accuracy of the results. The 
specific gravity of each solution was first taken. 100 grains 
measure at 60° Fahr. were then placed in clean, accurately 
tared and marked platinum capsules, weighing from 180 to 
200 grains each ; the fluids were then carefully evaporated 
to dryness on a water bath, those containing the potassium 
iodide being afterwards heated in an air-bath at 220° Fahr. 
till they ceased to lose weight, whilst those containing the 
zinc sulphate were dried at 220° Fahr. and afterwards heated 
to dull redness to drive off the last molecule of water 
^ The facts contained in this paper were accepted by the Committee 
of the Pharmaceutical Society of Great Britain, to be read before them, 
and subsequently, on the day advertised by them for its reading, rejected 
by the Council. 
