38 Observations and Experiments on Peruvian Bark. 
is not very strong, but when bark is well cured it is always 
perceptible, and the stronger it is, provided it be pleasant, 
the better may the bark be considered. In order to give 
bark the form of quill, the bark gatherers not unfrequently 
call in the aid of artificial heat, by which its virtues are de- 
teriorated, the fraud is detected by the colour being much 
darker, and upon splitting the bark, by the inside exhibiting 
stripes of a whitish sickly hue. In the form of powder, cin- 
chona is always found more or less adulterated: This must 
be recollected as applying to the English market. During a 
late official inspection of the shops of apothecaries and drug- 
ists, the censors repeatedly met with powdered cinchona 
Saene ahard metallic taste, quite foreign to that which 
characterizes good bark.* The best test of the goodness of 
bark, is afforded by the quantity of cinchona or quina that 
may be extracted from it; and the manufacturer should al- 
ways institute such a trial before he purchases any quantity, 
taking a certain number of pieces indiscriminately from the 
bulk. 
Before concluding, it may not be out of seasen to remark, 
that the sulphate of quinine, as it is generally termed, is not a 
perfectly neutral salt, but in the state of a sub-sulphate, and is 
judicious, since tartaric acid d 
occasions an insoluble tartrate which is precipitated. 
41 Mr. Thompson has suggested the probability of this circumstance having 
arisen from the admixture of a species of bark, lately introduced into Europe 
hipaa eae the cinchona floribunda, and which by an anal- 
ysis of M. Cadet was found to contain iron.—London Disp, Edit. 3, p. 247, 
+ Pharmacologia, Edit. 6, vol. ii, Pp: 163., . 
