MICROCHEMIS TR Y. 1 2/ 



consist of the double chloride of gold and theobromine 

 C 7 H 8 N 4 O a -HCl.AuCl 3 . 



n. Caffeine, Theine, Methyl-theobromine, Trimethyl-xanthin 

 C 8 H 10 N 4 O a + H,0. 



221. Molisch recommends (I, 7) gold 'chloride for the micro- 

 chemical recognition of caffeine. It is used in the same 

 way as for theobromine, and there are formed tufted ra- 

 diating needles of the composition C 8 H 10 N 4 O 2 .HCl.AuCl, , 

 which cannot certainly be distinguished from those of the 

 corresponding theobromine compound. 



Hanausek (I) has lately called attention to the fact that, 

 especially when the gold chloride solution contains more 

 than 3$ of the salt, a drop of it with concentrated hydro- 

 chloric acid will, in any event, form yellow crystals on evap- 

 oration. But these are distinguished from the caffeine- 

 gold chloride crystals by the fact that they never form 

 sharp-pointed or tufted needles, like those of the caffeine- 

 gold compound, but consist partly of very short crystals 

 arranged in zigzag, and partly of very long, delicate, yellow, 

 rod-like prisms and of plates with rectangular projections. 



Molisch gives also another method for recognizing caf- 

 feine. According to this, sections are warmed on the slide 

 in a drop of distilled water until it bubbles, then allowed to 

 dry at the ordinary temperature, and the residue is taken 

 up with a drop of benzol. On the evaporation of the benzol, 

 the caffeine is deposited at the edge of the drop in the form 

 of numerous colorless needles. 



o. Veratrine, C 37 H 63 NO n . 



222. Veratrine occurs, according to Borscow (I, 58), in 

 the subterranean parts of Veratrum album, especially in the 

 walls of the cells of the epidermis and of the bundle-sheath 

 (endodermis). This author used for the recognition of vera- 

 trine a mixture of one part of concentrated sulphuric acid 

 -with two parts of water, in which the sections to be exam- 



