GELATINIZATION OF TINCTURE OP KINO. 265 
displacement is much more fluid than that prepared by mace- 
ration ; the latter being generally too thick and viscid to pass 
through a filter, while the former is a perfectly limpid solu- 
tion. It is stated in the Edinburgh Pharmacopoeia that tinc- 
ture of kino cannot be made by displacement; but it is only 
necessary to mix the kino with a proper proportion of clean 
white sand, to enable the spirit to percolate through it with 
perfect facility. 
In the American Journal of Pharmacy for 1840, allusion is 
made to the preparation of this tincture by displacement, and 
equal quantities of kino and of sand are directed to be used in 
operating in that way. It is also stated, that tincture of kino 
thus made has been kept for more than twelve months without 
becoming gelatinous. 
In addition, however, to the adoption of percolation in pre- 
paring the tincture, the further precaution should be taken, of 
keeping it in well filled bottles, accurately stopped, so as to 
preclude, as much as possible, the access of atmospheric air. 
This precaution I conceive to be important. If a pint of the 
tincture be made, it should be put into two half-pint bottles, 
instea-d of keeping it in a quart or two quart bottle for dis- 
pensing, as is frequently the case. The contact of a large 
body of atmospheric air must undoubtedly tend to expedite 
the change, and it is evident, that long before the tincture 
has become gelatinous, a considerable proportion of the tannic 
acid will have assumed a new and altered condition, from 
which its medicinal properties will be greatly impaired. 
Ibid. 
