1 90 MR. E. SCHUNCK ON THE 



by the addition of alkali or by the temperature of the solu- 

 tion rising to any great extent above that of the atmosphere. 

 When dissolved in alcohol or ether, on the other hand, the 

 substance exhibits a much greater resistance to change than 

 when dissolved in water. I, therefore, soon abandoned all 

 idea of extracting the plant with the latter menstruum, and 

 had recourse to alcohol and ether. I shall refrain from giving 

 an account of the numerous experiments I made, which led 

 to no successful issue, but shall briefly describe the three 

 methods of preparation, which were attended with more or 

 less advantageous results. 



All three methods consist in extracting with alcohol or 

 ether. But, before commencing, it is necessary that the 

 plant should be thoroughly dried. The leaves alone being 

 gathered, which should only be done when not moistened 

 with rain or dew, are spread out in a thin layer in some 

 warm, dry place, as, for instance, near a stove or in a dry- 

 ing room. All yellow or decayed leaves should be rejected. 

 When they are perfectly dry they are carefully examined. 

 All those leaves which during the drying have become 

 brown, a result which takes place when the heat has been 

 too great, are cast aside, and only those are retained which 

 have a pale green colour. These must now be reduced to 

 a coarse powder, an operation easily effected if the leaves 

 be taken while still warm, as they are then quite brittle, 

 whereas if allowed to remain exposed to the atmosphere 

 they attract moisture again, and become flaccid and difficult 

 to pulverize. The powder must be kept warm until it is 

 used. 



I. The leaves thus reduced to powder being put in a dis- 

 placement apparatus, such as is used for the preparation of 

 tannic acid, are extracted with cold alcohol. The perco- 

 lating liquid is dark green. The extraction is continued 

 until the liquid runs through of a light green colour. Th^ 

 alcoholic extract is now distilled in a retort, until a great part 



