172 PIPERA GEJEJ. 



r 



tliese masses are slowly transformed into needle- shaped crystals 

 of piperin. [Fharmacograph ia) 



Chemical compodtion. — Black pepper contains an acrid resin, 

 a volatile oil, starch, gum, a small quantity of fatty oil in tlie 

 mesocarp, and about 5 per cent, of inorganic matter, besides the 

 2L[k'Aoidi piperine y and a volatile alkaloid wbicli is probably iden- 

 tical -with. j)i2)eridme. The acrid resin is dark-green, soluble in 

 alcohol, ether and alkalies, and, in connection with other 

 constituents of pepper, also in w^ater. C. Heisch (J.;m///5^, xi., 

 186-190) has shown that pepper should contain not less than 50 

 per cent, of starch, which is characterised by the smallness of its 

 granules. The essential oil has been examined by L. A. Eber- 

 hardt [Archiv. d. Phann. (3), XXV., 515-519) ;ithad a sp.gr. of 

 0-87352 at 15^ C, and showed a greenjsh colour, due neither to 

 chlorophyll nor to copper. At 22° the oil had a Isevorotatory 

 power of 3*2° in a column 100 mm. long. On rectification 

 a very small quantity passed over at 160^. Fractions obtained 

 at 170°, 176° and 180° were colourless ; that obtained at 190" 

 faint green, and that at 250° green, that passing over at 310 

 brown-green. Above 310° a brown, tenacious residue was 



which phenol could not be detected. The 170 frac- 

 tion, when rectified under reduced pressure, gave a terpene 

 boihng at 164°— 165°, and showed a left-handed rotation 

 of 7"6° in 100 mm.; it gave numbers agreeing with the 

 formula C'^H^^ 



The composition of the other fractions was much the same as 

 this. The oil consists of a Iscvorotatory terpene and isomeric 

 compounds of higher boiling point. {Journ. CJiem. Soc, Oct., 

 1887; Year^Book Fharm,, 1888.) 



Pure piperine crj^stallizes in colourless flat, four-sided prisms 

 of a glassy lustre and almost tasteless. As 



in 



u^ua 



yellowish 



in 



taste. It remains unaltered on exposure, has a neutral reaction 

 to test-paper, is nearly insoluble In water, and dissolves in vola- 

 tile oils, in 60 parts of cold ether LMerck), in 30 parts of c(^<i 



