ON THE PREPARATION OF TINCTURES. 
547 
si large scale lie believed it was impracticable. Tlie operation must be carried 
on by means of skilled labour, a common labourer could not do it; it required 
constant thought and attention. He had had nearly twenty-seven years’ ex¬ 
perience, and of all the assistants and apprentices he had had during that time, 
most of whom had endeavoured to comprehend the subject, only one, a Mau¬ 
ritius man, had really taken in the philosophy of the subject. It was not 
always convenient or practicable to adopt automatic means for the prevention 
of irregularity, nor could the operator always keep his eyes continually on the 
process. As a rule, therefore, it could not be placed in the hands of every 
one, and therefore could never be a process to be used by the majority of those 
for whom it was designed. 
The form of the apparatus was one of great importance. At first, and for 
a considerable time, he had employed a cylinder with a flat or slightly concave 
bottom, with an exit tube fixed in the centre, but finding that invariably there 
was a portion of the substance imperfectly acted upon in the angles at the 
bottom of the cylinder, he tried cylinders with funnel-shaped bottoms ; but in 
retaining the cylindrical form at all, there was the repeated inconvenience of 
some substances shrinking from the sides to an inconvenient extent when by 
any chance they were allowed to run dry before the operation was complete. 
Having these difficulties before him, and referring back to the dead space ob¬ 
served in the cylinders with flat bottoms, he repeated some operations in them, 
turned out the mark, and cut it vertically down the centre. The direction 
which the great bulk of the fluid employed had taken was so marked and 
uniform in each case, that he had been led to the adoption of an apparatus 
that answered perfectly, and wdiich was a portion of an elongated cone whose 
•sides formed an angle of 82° to the base line. The dimensions of one of such 
vessels he had in constant use, and which would be found generally useful, 
was twelve inches deep, nine inches broad at top, and six inches at bottom ; 
the bottom rather concave, with a tubular opening for arranging a tap. The 
apex of the cone was not good for ordinary purposes; for, in the first place, to 
hold a sufficiency of matter to be operated upon, it must be made of an incon¬ 
venient length, and secondly, it was liable to clog. It was somewhat singular 
that if the angle were too small, as in a common funnel, the fluid seemed to 
him to have a tendency, in some instances, to find its way down the sides of 
the funnel rather than through the body of the material. Those who were 
interested in carrying out this valuable and nice operation in a scientific man¬ 
ner would do well to study it in the fractional manner above described, for 
he was satisfied there was much valuable information yet to be learned from 
it. He quite agreed with Dr. Redwood that you cannot displace spirit with 
water, and with whatever liquid you commence your operation, with that you 
must complete it. When small quantities of dry matter are used, the quan¬ 
tity of spirit retained may not be worth saving, but larger quantities should 
be pressed, and the pressings set aside and properly labelled, to be employed in 
the commencement of the next operation on the same substance. This was 
one of the inconveniences of the process, involving the use of many bottles 
and much space, which few could afford. 
Mr. Hills said that at that late hour he would detain the meeting only a 
minute or two, to say that both Dr. Redwood and Mr. Deane in their interest¬ 
ing account of the process of percolation and displacement, admitted that it 
required the greatest nicety of manipulation, and that by an expert, to carry 
it out in a satisfactory manner. He (Mr. Hills) was convinced that mace¬ 
ration with agitation was the best way of making tinctures. He had made 
a tincture at the same time Dr. Redwood was making one by his automatic 
process, and although he had only six-and-forty hours to make it, in order to 
compare with Dr. Redwood’s, it was found to be quite equal to the latter. 
