SOLUTIONS OF IODINE AND OTHER PREPARATIONS. 607 
tincture made with the dried peel. He should, however, like to know what 
proportion of fresh peel Mr. Martindale would substitute for the dried. 
Mr. Martindale thought about double the quantity, the peel being cut thin. 
Mr. Sandford considered one and a half for one a fair proportion, the thinly- 
cut fresh peel containing much less of the inert white interior than the dried. 
A Member remarked that there was a deficiency of tests given in the Phar¬ 
macopoeia for some of the articles ordered. For instance, there was no che¬ 
mical test for glycerine. 
The Chairman said it certainly appeared to him to be a defect that in the 
Pharmacopoeia there was no test but that of specific gravity for glycerine, 
which was daily becoming more and more important. It was a fact that some 
specimens of glycerine possessed all the physical characteristics required in the 
Pharmacopoeia which were not fit to be used in making the tannic acid glycerine 
and the gallic acid glycerine. 
Dr. Redwood said it was new to him to hear that the Pharmacopoeia was 
deficient in the number of tests ordered. A statement had, indeed, been made 
in quite the opposite direction during the discussion of this subject, namely, 
that the Pharmacopoeia required too much in the use of chemical tests and in the 
requirements of purity in the substances employed. He was not prepared to 
say that there might not be individual cases—he had no doubt there were, and 
the one referred to might be of that description—where the tests were not so 
complete as they might be, or as it was desirable that they should be. It was^ 
however,—and he had adverted to the fact before—absolutely impossible to 
give such a complete system of tests of the substances ordered to be used in 
medicine as would ensure the absence of all impurities in them without greatly 
complicating the work, and enlarging it to an extent which would be very un¬ 
desirable. Whilst they gave the leading tests for- indicating the principal 
impurities most likely to occur, and which it was most important to guard 
against, they must at the same time leave much to the knowledge, skill, and 
judgment of those who had to put the work into effect. And, therefore, whilst 
they were educating their young men, and enabling them to provide against 
the introduction of such impurities in medicines as-would interfere with their 
efficacy, they must from time to time, in successive editions of the Pharma¬ 
copoeia, increase the number of tests, as they had done in those which had 
recently appeared. Rut he could not say that he ever expected to see a 1 hai- 
inacopoeia that would give tests for the detection of all impurities. 
At the conclusion of the meeting, Dr. Redwood made some remarks on the 
preparation of the diluted nitro-hydrochloric acid of the Pharmacopoeia, lie 
said this had already been made the subject of several communications by 
gentlemen, who alluded to the fact that, when made as directed in the Pharma¬ 
copoeia, it was liable to considerable variation, in strength, arising from the loss 
of some of the evolved gases. Mr. Porter had suggested a special apparatus for 
its preparation, by which the loss of gas was avoided; but Mr. Porter’s^appa- 
ratus, although ingenious, was rather complicated and expensive. Mr. Porter, 
in his paper, alluded to the use of a more simple arrangement, but did not re¬ 
commend it. Now, he (Dr. Redwood) found that by using two Winchester 
quart bottles, putting the mixed acids into one and the water into the other, 
and connecting the bottles by a tube partly of glass and partly of india-rubber, 
the loss of gas may be almost entirely prevented, and a uniform product 
obtained, which nearly answered to the tests given in the Pharmacopoeia. 
Mr. Tilden said he thought in one respect the product, in whatever way it 
might be made, would not answer to the Pharmacopoeia test, and that was in its 
neutralizing power. He found by calculation that the acids, in their unmixed 
state, had less neutralizing power than was assigned to them when mixed. Rut 
he had also shown that the acids, if mixed at once with the water, yielded a 
