EXPERIMENTS ON LIVING CINCH ONE. 
Moisture lost by bark on sulphuric acid 67’5 per cent. 
In fresli bark. 
In 100 parts of juice. 
Total alkaloids 
6-10 
1T7 
Quinine 
1-15 
0-31 
Cinchonidine 
3 - 65 
0-51 
Cinchonine 
1-30 
0-35 
whence, by an obvious calculation, in the sample of fresh bark the respective alkaloids 
existed as follows : — 
In natural 
solution. 
In an insoluble 
state. 
Total in bark. 
Total alkaloids 
0-82 
5-28 
6-10 
Quinine 
0-22 
0-93 
M5 
Cinchonidine 
0-35 
3-30 
3-65 
Cinchonine 
0-24 
1-06 
1-30 
It thus appears that the greater part of the alkaloids is contained in the bark in the 
solid state ; none can be in the free state, on account of the excess of quinic acid and 
cinchona tannin. Hence it must be concluded that six-sevenths of the alkaloids exist 
in the cells of this bark as insoluble tannates, the remaining seventh mainly existing in 
solution as quinate, though the solution is of course saturated with tannate in addition. 
These combinations of the alkaloids with tannin are very sparingly soluble in cold 
water. The whole state of things in the bark resembles the equilibrium of solution and 
precipitate which would result from a mixture of tannin, alkaloid, and quinic acid. The 
quinic acid is only able to decompose a small portion of tannate, and the tannin is not 
able to precipitate the whole alkaloid from solution. Actual trial with the respective 
substances produces these effects. It is to be remarked that there is no marked difference 
in the proportions of the respective alkaloids which exist, in one or the other state, in 
the cell-contents or in the liquid which moistens the whole. This is in harmony with 
the impression, to which all the facts at present known seem to conduce, that all the 
cinchona alkaloids are physiologically equivalent. 
From the nature of the weak compound that quinovin is able to form with the cin- 
chona alkaloids, it is evident that none could exist in the presence of quinic acid. 
Nearly the whole of the quinovin is to be found in the bark after the juice has been 
squeezed out. The clear juice only contains a very small amount, and its presence is 
readily explained by the faint solubility of this substance in water. 
The whole of the quinovin exists therefore in the insoluble and free state. 
No thoroughly accurate means of determining the amount of the cinchona tannin has 
yet been devised ; neither gelatin, animal membrane, nor even plumbic acetate removes 
it completely from solution. Tartar emetic succeeds better ; but the precipitate has a 
variable composition, and also removes the alkaloids in part. By washing these out 
