ON THE AMOUNT OF ALKALOIDS IN CINCHONA BAKK. 
51 
for the preparation of his so-called quinium, could be easily adapted for my 
purpose ; and the result of my experiments proved that I had made a right 
choice. My method, which has been applied to the investigation of the 
Neilgherry barks, is the following :— 
The powder of the bark is dried at 212° Fahr., and the weight ascertained 
in the dry state. If possible, it is always preferable to use the same quantity. 
It is now mixed with a quarter of its weight of slaked lime, and this mixture 
boiled with ten times its weight of spirit of sp. gr. 0'85 during five minutes. 
The whole is now put into a filter, and exhausted by successive quantities of 
boiling spirit, making the whole quantity of spirit used equal to twenty times 
the weight of the bark. The alcoholic solution, after having been acidulated 
by dilute acetic acid, so that litmus paper becomes reddened, is evaporated 
on a water-bath till all the alcohol has been expelled. The residue of the 
evaporation is now repeatedly treated with water till the filtered liquid is 
no longer rendered turbid by an alkali. The watery solution thus obtained 
contains all the alkaloids, whilst the quinovic acid, fatty and resinous mat¬ 
ter, etc., remain upon the filter. If this filter, with its contents, be duly 
treated with milk of lime, the quinovic acid can be determined. The watery 
solution of the alkaloids is next brought to a small volume by evaporation 
on a water-bath, and then mixed with an excess of slaked lime, by which 
the alkaloids are precipitated. The whole is now thrown upon the smallest 
possible filter and washed with a minimum quantity of cold water. If 
properly managed, the quantity of water necessary to remove the colour¬ 
ing matter is so small, that the loss of alkaloids by their little solubility 
in lime-water can be neglected; and if in a series of investigations care is 
but taken to work under the same conditions, as to size of the filters, etc. etc., 
the small loss before mentioned has not the least influence on the com¬ 
parability of the results. After the filter has been properly washed, it is 
dried and boiled repeatedly with alcohol of 082, till the alcohol dissolves 
nothing more. After filtration the slightly coloured alcoholic solution is 
evaporated in a small weighed platinum vessel, and the residue heated on 
the water-bath until its weight ceases to diminish. The amount of the 
alkaloids in the bark is now known, and to ascertain the quality of the 
different alkaloids, they are dissolved in the smallest possible quantity of very 
dilute acetic acid. Sometimes there remains a trace of resinous matter undis¬ 
solved, but in the majority of cases this trace need not be noticed. If, 
however, in an exceptional case, the resinous matter is in such quantity 
that it can be weighed, its weight must be ascertained and subtracted from 
the amount of alkaloids. The acetic solution of the alkaloids is now placed 
in a closed funnel, provided with a cock, and agitated with a slight excess 
of caustic soda and a quantity of ether equal to fifteen times the -weight of 
the alkaloids. After this agitation, the whole must stand at least six hours ; 
for, although cinchonidine and quinidine are sparingly soluble in ether, a 
large amount of them is dissolved upon the first agitation, but is separated in 
crystals after a few hours. The ethereal solution is now evaporated, and the 
residue heated on a water-bath till its weight remains constant. This residue 
is quinine, containing traces of cinchonidine, quinidine, or cinchonine, and in 
many cases a large amount of the still unknown fusible alkaloid. By the 
known reactions of chlorine and ammonia, and by the preparation of herapa- 
tliite, the real nature of this residue can be ascertained. The alkaloids which 
have not been dissolved by the ether are now again dissolved in the smallest 
possible quantity of dilute acetic acid, and this solution mixed with a few 
drops of a concentrated solution of iodide of potassium. After stirring the 
liquid with a glass rod, there will appear a sandy crystalline precipitate if 
quinidine is present. In such case, the hydriodate of quinidine is collected 
