96 



The similarity in the physiological action of Pi2)er ovatnm to that of the 

 medicinal pellitory has already been noticed, and in the latter case the action is 

 usually attributed to a resin, about the properties of which, however, little is 

 known.* The resin obtained from Piper ovatum was fully examined in the hope 

 of separating some crystalline active substance from it. It was soon found that 

 the resin was not a single substance, in spite of the long process of purification to 

 which it had already been submitted. It was further purified by dissolving it in 

 ether, and fractionally precipit^ating the ethereal solution with light petroleum, in 

 which the active constituent is nearly insoluble ; by this means, it was obtauaed 

 lighter in colour but still resinous. The resin was again dissolved in ether, and 

 the solution shaken with weak aqueous ammonia, which removed a further 

 quantity of inactive material. After the ethereal solution had been dried with 

 calcium chloride, a resin, which was quite inactive, separated from the liquid. 



The ethereal solution, when spontaneously evaporated, left a highly active 

 substance which, however, was still resinous, and refused to crystallise. The 

 resin was next dissolved in alcohol, and the solution fractionally precipitated by 

 the addition of water ; the first fraction was resinous and nearly inactive, the 

 later fractions were lighter in colour than the first and highly active. On 

 repeating the process on the later fraction, a bulky but very light mass of 

 feathery crystals separated, which were nearly colourless and more active than 

 any substance previously obtained. This material was, with difficulty, recry- 

 stallised several times from dilute alcohol, and lastly from hot, light petroleum. 

 A further quantity was obtained from the purified resin by shaking the ethereal 

 solution with ammonia, dissolving the residue in alcohol, and precipitating 

 the solution with light petroleum, the precipitate being again dissolved in 

 alcohol and reprecipitated with petroleum until it was capable of crystallising. 



As will be inferred from the details which have been given, the separation of 

 this crystalline active substance from the colouring matter, fat, wax, and resin 

 which so obstinately adhere to it proved to be a very tedious operation, especially 

 troublesome when the object was to obtain a sufficient quantity for analysis. 

 Much time was spent in trying various methods of extracting the substance 

 from the plant, and in purifying the product ; the most successful plan was 

 found to be the following, which, however, is still long and laborious. 



The dried and finely-powdered material (leaves, root, and stem, all of 

 which contain the active constituent) is repeatedly extracted with hot, light 

 petroleum (boiling below 80°) until the active substance is almost entirely 

 removed ; the removal of the last traces is very troublesome. The active 

 constituent is not readily soluble in light petroleum, but it is found to be advan- 

 tageous to use this liquid because it removes a smaller quantity of other substances 

 than is the case with better solvents of the active constituent, such as alcohol, 

 ether, chloroform, or acetone, which dissolve so much colouring matter, resin, 

 and fat that the subsequent purification of the active substance is very much 

 lengthened. 



The greater part of the light petroleum is distilled from the solution, and 

 the residue is well shaken with alcohol (60 per cent. ). By repeating this opera- 

 tion several times, nearly the whole of the active constituent passes into the 

 alcohol, whilst most of the colouring matter, fat, essential oil, &c., remains 

 in the layer of petroleum. On concentrating the dilute alcoholic solution, 

 a considerable quantity of semi-crystalline active substance separates along 

 with green colouring matter ; this is partially purified by repeated crystallisation 

 from dilute alcohol. By this means much of the resin, which so obstinately 

 clings to it, is removed, and more is separated by shaking an ethereal solution 

 with dilute aqueous ammonia. The dried ethereal solution may then be preci- 

 pitated by the addition of small quantities of light petroleum, which throws 

 out the resin in the first fraction, whilst the later fractions are crystalline and 

 consist of the nearly pure active constituent. Finally, the s\ibstance is recrys- 

 tallised by adding dry ether to its solution in absolute alcohol, and allowing 

 the solution to evaporate spontaneously. The crystals which separate are dried 

 on a tile in the air or in a desiccator ; at 100° a little decomposition occurs, 

 and the crystals become slightly yellow. 



The preparation of sufficient material for analysis occupied a very long 

 time, since the best process for isolating it is rather wasteful, as some of the 

 active constituent is thrown down along with the resin during the fractional 



* See the following papor. 



