ON THE PREPARATION OF TINCTURES. 
533 
then stated, that having recently been called on by a physician to supply 
oxygen for a patient, he had procured a Barth’s apparatus and found it ex¬ 
tremely convenient and easy of management; that by a graduated rod attached 
to the cylinder, the proportions of oxygen and atmospheric air could be regu¬ 
lated with the greatest accuracy ; and when some objection was raised as to 
its expense, he had replied that the apparatus might be hired for a moderate 
charge. He would not have trespassed on the time of the meeting with this 
explanation, but that he felt it due to the inventor of so excellent an apparatus 
that the error should be corrected in the place in which it had been reported 
to have been made. 
ON THE PREPARATION OF TINCTURES, 
BY PERCOLATION, MACERATION, AND THE AUTOMATIC PROCESS, WITH 
REMARKS ON THE NEW METHOD INTRODUCED IN THE BRITISH 
PHARMACOPOEIA, AND SUGGESTIONS FOR ITS IMPROVEMENT. 
BY THEOPHILUS REDWOOD, PE.D., E.C.S., 
PROFESSOR OF CHEMISTRY AND PHARMACY TO THE PHARMACEUTICAL SOCIETY. 
The introduction of a new process for the preparation of tinctures which has 
been adopted for most of the tinctures in the British Pharmacopoeia, while 
other similar preparations described in that work are directed to be made by 
processes differing not only from it, but also to some extent from each other, 
seems to render the present a suitable time for discussing the relative merits 
of the several processes for the production of this, the most numerous and not 
the least important class of preparations used in medicine. 
Of the two principal processes hitherto employed in the preparation of 
tinctures, one only, namely maceration, has been recognized in the London 
and Dublin Pharmacopoeias. The other process, that of percolation, was 
sanctioned by the Edinburgh College in their Pharmacopoeia of 1839, and it 
has also been largely applied by some practical pharmaceutists in operations 
to which it has been found applicable. 
The process of percolation or displacement was introduced in pharmacy 
about thirty years ago, and was first brought under the notice of the Pharma¬ 
ceutical Society by Mr. Deane. Since that time its use has been gradually 
extended both abroad and in this country, but although it has been generally 
admitted that it offers some advantages over other processes in effecting the 
exhaustion by liquid menstrua of many vegetable substances used in medicine, 
3 7 et at no time nor in any country has it more than partially superseded the 
older, more familiar, and more simple process of maceration, and especially in 
the preparation of tinctures. 
In conducting the process of percolation, the solid substances operated 
upon are required to be in a uniform and rather minute state of division, so 
that they may admit of being so packed in the percolator that the spaces 
between the separate pieces or masses of solid matter shall not be very sensibly 
greater than the natural spaces existing in the tissues of which the substances 
are composed. The more finely divided the solid substance is, provided 
that when packed in the percolator it will admit of percolation, the more 
perfect will the process be ; but some vegetable substances, when in a finely 
divided state, and in contact with the menstruum, become compacted into so 
dense a mass that the liquid will not pass, and therefore the process does not 
admit of application in such cases, under the most favourable circumstances 
and with the best results. The reduction of the solid substances to the most 
suitable state of division, and the packing of these with the proper amount 
and kind of pressure, involve the exercise of much judgment and skill. A 
