SECT. XII. ACIDS. 415 



been minutely analyzed. The following are the 

 most remarkable : the inspissated juice of Lettuce, 

 which resembles opium much in its appearance, is 

 obtained by the same means, and possesses the 

 same medical virtues ; the leaves of Atropa Bella- 

 donna or Deadly Nightshade, and indeed the whole 

 plant ; the leaves of Digitalis purpurea or Fox- 

 glove ; and lastly the following plants, Hyoscy- 

 amus niger, Conium maculatum, Datura Stramo- 

 nium, and Sediim palustre ; with many others 

 belonging to the natural order of Luridse. 



SECTION XII. 



Acids. 



ACIDS are a class of substances that may be dis- Contained 

 tinguished by their exciting on the palate the sen- 

 sation of sourness. They exist not only in the 

 animal and mineral, but also in the vegetable king- 

 dom ; and such of them as are peculiar to vege- 

 tables have been "denominated vegetable acids. 

 Of acids peculiar to vegetables chemists enumerate 

 the following : the oxalic, acetic, citric, malic, 

 gallic, tartaric, benzoic, and prussic, which exist 

 ready formed in the juices or organs of the plant, 

 and are accordingly denominated native acids ; 

 together with the mucous, pyromucous, pyrotartar- 

 ous, pyrolignous, camphoric, and suberic, which do 

 not exist ready formed in the plant, and are hence 



5 



