FERMENT OILS. 353 



The fermentive principle of the leaves of plants, or so-called 

 " plant ferment " is obtained as follows : — Select the young leaves 

 and macerate them at once, or as soon after gathering them as 

 possible in sufficient cold water to cover them ; continue the 

 maceration for 12 hours; press out the liquid, filter and add an 

 equal volume of strong alcohol ; the liquid thereupon becomes 

 cloudy and after 12 hours yields a greyish white deposit. The 

 liquid is then filtered, and this deposit left on the filter is the 

 " ferment." It is to be washed with alcohol and removed from the 

 filter for use. 



The cause of the formation of these oils has not been clearly 

 explained, but it may be due to the decomposition of certain 

 glucosides, organic bodies of great chemical complexity, which are 

 in some cases resolved, when left in contact with certain protein 

 substances and water, into sugar and an essential oil. An example 

 of a " protein substance " is Avenin or Aveneine (Series i., p. 170) 

 which exists in the husk of oats {Avena sativci). To prepare it : — 

 grind the grains with water, dilute the pasty mass with water ; 

 after 12 hours strain and filter the liquid, precipitate with acid and 

 purify the precipitate by means of alcohol and ether. 



Another authority describes the preparation thus : — The grain, 

 reduced to a state of powder or meal, is washed on a sieve, and the 

 milky liquid, after being allowed to deposit its starch is heated to 

 about 200° Fahr. to coagulate the albumen ; when cold, acetic acid 

 is added as long as a white powder falls, which is Avenin. This is 

 collected on a filter, drained and dried at a gentle heat. It is a 

 nitrogenous compound analogous to and probably identical with 

 casein. It is greyish-white in colour, dissolves readily in water, 

 does not coagulate by heat, dissolves also in excess of acetic and 

 hydrochloric acids. 



Gluten is a mixture of difterent '•' protein substances." It is best 

 obtained by kneading wheat-flour under cold water until the water 

 passes from it clear and without a milky appearance. When fresh 

 it is greyish-white, very viscid, glutinous, elastic, tasteless, and of 

 insipid odour. 



By reason of the very volatile nature of some " ferment oils," it 

 is necessary to evaporate off the ether or other solvent by which 

 they have been removed from the aqueous distillate of the 



