MICROCHEMISTR Y. 121 



the older parts it incrusts especially the cell-walls of the 

 xylem. 



For its microchemical recognition O. Herrmann treats 

 the sections first with alcohol and then adds dilute nitric 

 acid (one part of acid to about fifty parts of water). The 

 golden-yellow color passes over at once into brownish yellow, 

 and soon golden - yellow 

 star-shaped crystals are de- 

 posited, while the cell-sap 

 becomes gradually color- 

 less. The same crystals of 

 berberin nitrate may be ob- FlG . 3I ._ G rou P s of crystals of berberin m- 



fpin^rl h\/ nlarincr \\\e> QRP l r ate obtained by placing longitudinal sec 

 Dy placing tne SeC- t , ns of the bark of Berberis vulgaris in a *% 



lions directly in dilute nitric 



acid. I use 2 parts of the officinal nitric acid in 100 parts 

 of water. The berberin nitrate separates out in the form 

 of clustered crystals (cf. Fig. 31) in the interior of the ber- 

 berin-bearing cells. These crystals are strongly doubly 

 refractive and so far pleochroic ( 356, note) that they 

 appear quite colorless in a certain position of the nicols, 

 while after rotation through 90 they appear deep golden 

 yellow. 



Herrmann also used ammonium sulphide, which gives a 

 brownish color with it, for the recognition of berberin. 



Rosoll used a solution of iodine and potassium iodide for 

 the same purpose. This is added to the sections in small 

 quantity after preliminary treatment with alcohol. There 

 are then formed very characteristic hair-like crystals, ar- 

 ranged in tufts, which are green or, in the presence of large 

 quantities of the reagent, yellowish or reddish brown, and 

 are soluble in sodium hyposulphite. The crystals thus 

 obtained cannot be preserved in Canada balsam, according 

 to my experiments. 



If hydrochloric acid be added to the yellow aqueous ex- 

 tract of the dried bark, there are formed, according to 

 Naegeli and Schwendener (I, 504), numerous yellow and 

 often radially grouped needle-like crystals of berberin chlo- 

 ride. 



