THE CHEMISTRY OF FRUIT RIPENING. 157 



after fermentation. In the red wines, from 0.08 to 0,2 per cent, of tannin is 

 found. Tlic decomposition of tannin, by a fermentation producing sugar, has 

 been mentioned under tlic head of sugars. Tannin is also lialjlc to oxidation, 

 ■\vitli various [)roducts not including sugar. 



Tlic vegetable kingdom furnishes numerous compounds, known as glucosides, 

 which are capable of definite and distinctive fermentations, one of the fermen- 

 tation-products in each instance being sugar. A number of these glucosides 

 arc found in fruits. One of the most important of tlieso is amyfjdaUn, a glu- 

 coside found in the fruits, leaves, etc., of jjlantsof tlie almond family, especially 

 in the kernels of tlie bitter almond, peach and chcny, the leaves of the cherry- 

 laurel, and the bark of the wild cherry. 



AmygdaUn, when obtained pure, is a wliitc, odorless solid, with a taste both 

 sweet and bitter. Taken alone, it is not poisonous, even in considerable quan- 

 tities. But if mixed with a sub>tance named emulsin, and wetted, amygdalin 

 begins at once to Ijrcak up, with formation of three otlier compounds as 

 follows : 



r 1. Bitter Aliiioiul Oil, 106 parts. 



j 2. Hydrocyanic Acid (or " Prussic Acid-'), 



Amyo-daliii, 457 parts (bj' contact with , 



eniidsin), produces: 1 27 parts, 



L 3. Glucose, 360 parts. 



In the plant, ain3'gdalin is accompanied with the emulsin needful for its fer- 

 mentation. During the ripening of the fruit, and in the maturity of the 

 leaves and other parts, the amygdalin is constantly though slowly being trans- 

 formed into tlie three products above named. The bitter almond oil and 

 hydrocyanic acid are volatile and odorous and give the pleasant odor of peach 

 kernels, almonds, etc., familiar to every one. The rapidity of the chemical 

 change is chiefly governed by the proportion of moisture, being greatly acceler- 

 ated by wetting the bruised kernels or leaves, and stopped altogether by drying, 

 while the moisture of the living plant permits only a gradual rate of the trans- 

 formation. One of the products of this change is poisonous, the well-known 

 hydrocyanic acid, or prussic acid, one-tenth of a grain of which is a full medi- 

 cinal dose. The bitter almond oil (known to chemists as benzoic aldehyde and 

 easily oxidized to benzoic acid) is not in the least poisonous (when separated 

 from the hydrocyanic acid). It will be seen from the numbers of parts result- 

 ing from the change (as given above; that one part of hydrocyanic acid, and 

 four of bitter almond oil, are produced by sixteen parts of pure amygdalin. 

 The amygdalin of the shops, in Europe, where it is somewhat used to generate 

 hydrocyanic acid in medicine, yields from 1-20 to 1-25 of its weight of hydro- 

 cyanic acid. In exposure to the air, the hydrocyanic acid, being very volatile, 

 is quickly dissipated, while the bitter almond oil vaporizes more slowly. In 

 most fruits of the almond family, the amygdalin and its products are obtained 

 chiefly or only from the kernel, hence the well-known flavoring effect of leav- 

 ing in the stones, or a few cracked stones, in canned fruits. Some of these 

 fruits, however, have the amygdalin deposited in the sarcocarp (or edible por- 

 tion). This is stated to be the case with black cherries. 



The almond flavor is a very grateful accompaniment of fruits and flowers, 

 and it is provided by nature in safe and wholesome proportions, l)ut it has been 

 so tampered with by the art of man that its use is now beset with dangers of 

 several sorts. In the first place, there is the danger in concentrating what the 

 Creator has diluted. The oxygen of tlie air itself is poisonous when concen- 

 trated. Bungling art is almost sure to "o'erstepthe modesty of nature"' by 



