ON THE PREPARATION OP TINCTURES. 
541 
4. Recovery of the valuable part of the product. This is more com¬ 
pletely effected by this process than it can be by maceration and expression. 
On the other hand, there are some objections that maj'-bc urged against the 
process of percolation, and especially against its general application for the 
preparation of tinctures. 
1. It requires skill and knowledge for its successful application, which can 
only be acquired by much experience ; whereas in making tinctures by mace¬ 
ration, unskilled labour, such as that of apprentices, can be applied. 
2. Although the time involved in making a tincture by percolation is com¬ 
paratively short, yet during the whole of this time the attention of the ope¬ 
rator is required, whereas in operating by maceration such is not the case. 
3. Although a larger proportion of the strong tincture is recovered by 
percolation and displacement than by maceration and expression, yet in the 
former case, when legitimately conducted, the last part of the tincture is only 
recovered at the cost of an equal volume of spirit which is used for dis¬ 
placement. 
4. There is a strong temptationTor the use of water as a displacing liquid, 
and great danger in using it of diluting and otherwise injuring the tincture. 
The process of maceration, which is the oldest and most familiar mode of 
operating, although it presents the advantage of great simplicity, being a 
process that any one can perform, is nevertheless by no means a perfect pro¬ 
cess. As a means of effecting the exhaustion of the substances operated upon 
it is inefficient, unless the ingredients be frequently agitated, and this necessary 
part of the operation is often neglected or irregularly attended to. Then the 
period required for maceration is inconveniently long, and as it is difficult, 
with the large number of tinctures to be made, to keep a correct register of 
the times at which the process should terminate, much irregularity often 
attends this as well as other parts of the process. 
Dr. Burton s modification of the process of maceration was suggested in 
1844,* with the view of obviating the necessity for agitation while the ingre¬ 
dients are macerating, and it consists in suspending the solid ingredients, 
enclosed in a bag, near the top of the liquid in which they are macerated, 
instead of allowing them to remain at the bottom. The same principle had 
previously been applied and has frequently been advocated for the preparation 
of infusions, and its suggested application for the preparation of tinctures 
would probably have been more extensively tried if a suitable apparatus for 
the purpose had been devised. Some years ago Mr. Samuel Gale, who was 
then my laboratory assistant, induced Mr. Green, of Lambeth, to make some 
stone jars with perforated diaphragms that could be fixed at any required 
distance from the bottom, with a view to their application for carrying out 
this process ; but the arrangement of the jar did not fully realize the intended 
object, as the solid ingredients placed on such a diaphragm, and forming a 
solid bed across the column of liquid in the jar, was found to obstruct the 
circulation contemplated by Dr. Burton. 
In the ne w process of the British Fharmacopceia we have another modifica¬ 
tion of the process of maceration. In this we are directed to macerate the 
ingredients, with occasional agitation, for forty-eight hours with three-fourths 
of the spirit, then to turn the ingredients into a percolator, and when the 
liquid has ceased to pass, to add the remaining fourth of the spirit, and allow 
this to percolate through; then to subject the contents of the percolator to 
pressure, aud finally to make up the whole to a stated quantity by further 
addition of spirit. The object here seems to have been to remove the principal 
objection that attaches to maceration by reducing the time occupied in the 
2 o 
VOL. V. 
* ‘Pharmaceutical Journal,’ vol. iv. p. 4-69, 
