PEPPER 145 



8 per cent, which crystallizes in colorless, tasteless, 4-sided prisms 

 which are colored bright green by means of concentrated sulphuric 

 acid and formaldehyde, and with potassium hydrate or sulphuric 

 acid give a red color; piperidine, a colorless liquid alkaloid, which is 

 a derivative of piperine, about 0.5 per cent; a pungent resin, chavicin; 

 starch, 25 to 40 per cent; tannin; proteins, about 10 per cent; ash, 

 about 5 per cent. 



Black pepper should yield not less than 6 per cent of a non-vola- 

 tile ether extract nor less than 25 per cent of starch. The ash should 

 be not more than 7 per cent, of which only 2 per cent is insoluble in 

 hydrochloric acid. The crude fiber should be not more than 15 per 

 cent. 



Piperine is rather easily prepared from white pepper as follows: 

 The ground pepper is mixed with an equal weight of lime and a small 

 quantity of water is added. The mixture is heated to boiling for 

 about fifteen minutes, and is then evaporated and carefully dried 

 upon a water-bath. The residue is powdered and extracted with 

 ether. The ethereal solution contains the piperine, which separates 

 in the form of crystals. It is purified by recrystallization from hot 

 alcoholic solutions. 



Piperine is a weak base, dissolving in dilute acids without forming 

 salts and on this account may be separated from acid solutions with 

 petroleum ether. It forms crystalline double salts with platinic 

 chloride, mercuric chloride and iodin-potassium-iodide. At 25 C. 

 one part of piperine is soluble in 15 parts of alcohol; 36 parts of ether 

 and 1.7 parts of chloroform. It is nearly insoluble in water. The 

 individual crystals formed on a microscopic slide from hot alcoholic 

 solutions of piperine vary in length from 0.1 mm. to 1.5 mm. 1 Iso- 

 lated aggregates are also formed. As in cubebin we find numerous 

 oily-looking drops of the amorphous substance, but with piperine 

 they often have the outline of crystals, as if the latter were first 

 formed, and later transformed by fusion or otherwise into the amor- 

 phous material. On the other hand the crystals grow, on long 

 standing, at the expense of the drops. In sections of the crude drug 

 it is not at all uncommon to find in the oil secretion cells the charac- 

 teristic crystals of piperine. 



Standard of Purity. Black pepper is the dried immature berry of 

 Piper nigrum L. It contains not less than QT^O per cent of non- 

 volatile ether extract, not less than 30 per cent of starch, nor more than 



1 For micro-photographic illustration of crystals of piperine, consult Kraemer's 

 Applied and Economic Botany, pp. 161, 771. 



