ON PERCOLATION. 
441 
cure Barth’s apparatus for compressed oxygen, and he had found it clumsy, 
difficult to use, and very expensive. Mr. Bobbins, by his process, had obviated 
these objections. The difference in the cost of the oxygen by this and by the 
ordinary process of production, would not, he thought, be sufficient to inter¬ 
fere with its use as a remedial agent when the facility of its production was 
considered. 
ON PERCOLATION. 
BY MR. TIASELDEN. 
Some apology appears almost necessary for again bringing so soon before 
you the subject of Percolation and Percolators, but when I remind you that 
the British Pharmacopoeia orders percolation combined with maceration to be 
employed in the preparation of thirty-nine tinctures and nine extracts, fluid 
and solid, that, I feel sure, will be a sufficient excuse for me. Now, feeling 
pretty certain that the process of percolation would be carried out to some 
extent in the B. P., I had entertained a faint hope that a percolator adapted 
to our requirements would have been sketched out for us; but, like the expec¬ 
tations of many others upon other points, mine upon this were not to be 
realized. It is not my intention to occupy your time by explaining how I have 
proceeded when percolating, because every one who has been in the habit of 
carrying out the operation knows as well as I do, and many much better, that 
it is just one of those things which can only be acquired by practice, and that 
is why each one likes his own mode of proceeding the best, although he may 
be quite willing to admit that his product is no better than his neighbour’s, who 
slightly varies his modus operandi. A good manipulator will percolate (in the 
strict sense of the word) with almost anything, from a bottle with the bottom 
knocked out to the finest conical or cylindrical percolator ; but a bad, unob¬ 
servant manipulator will never percolate well with anything. My real object 
to-night is to show you a percolator which I have had made for myself, suit¬ 
able for the usual process of percolation, and also for that of maceration and 
percolation as directed in the B. P. If not trespassing too much upon your 
time, I should like to tell you that my first real difficulty in percolation was to 
find a percolator that was not likely to break easily, and the first I had was 
one of Ayliffe’s, made, percolator and receiver, of brown stone-ware. This soon 
got out of favour, as I could not see what product I was getting, and very 
soon the percolator or conical tube was cracked and leaked without any reason 
for the same. I then had one made of block tin, which I have used for some 
years, and which answered very well. I know that there are objections in 
theory to the use of any kind of metal, and some may be ready even now to 
say that it will change the colour of some of the tinctures, but practice proves 
the contrary. Now with the British Pharmacopoeia came another trouble. 
The directions there given are that the material is to be macerated with three- 
fourths of the spirit menstruum for forty-eight hours, agitating occasionally ; 
then transferred to a percolator; and when the fluid ceases to pass, pour into 
the percolator the remaining spirit. Now this implies one of two things,— 
either maceration in one vessel and percolation in another, or maceration and 
percolation in one and the same vessel. The employment of two vessels occa¬ 
sions extra labour, loss of time, and loss of material. Now I could not mace¬ 
rate with three-fourths of the material in my old friend, because the liquor 
would run through as soon as put in. Hooked at my glass percolator made by 
the York Glass Company; it would do for small quantities, but I wanted one 
for large quantities, three or four gallons. Glass, then, was out of the ques¬ 
tion, especially as one of the extracts requires hot water. I then applied to 
Messrs. Maw, to make me the one you see here to-night, of block tin, the 
