8 STUDY OF NUTS MICROSCOPIC IDENTIFICATION. 



to injury from late frosts, so that except in favored localities the 

 crop is rarely a success. It is grown commercially in parts of Cali- 

 fornia and the culture will probably extend eventually to a few 

 other States as favored localities are discovered and varieties are 

 originated which are less exacting in the climatic conditions to which 

 they seem suited. 



COMPOSITION AND USES. 



The proportion of kernels to shells of almonds varies between wide 

 limits, depending upon the thickness and density of the shell and 

 the plumpness of the kernel. Two samples of soft-shelled almonds 

 examined by the writer contained 61.2 and 63 per cent of kernels, 

 respectively, while a sample of hard-shelled almonds contained but 

 36.1 per cent of kernels. These are fairly representative of the re- 

 sults obtained by other investigators, but of course do not represent 

 extreme cases. 



The chemical composition of the almond kernel, as well as that of 

 most of the other nuts here considered, has been investigated by a 

 number of chemists and analyses are given in most of the standard 

 works on the composition of food products. The bitter almond 

 differs slightly in composition from the sweet almond and contains 

 in addition from 1 to 3 per cent of the glucosid amygdalin l and a 

 small amount of the ferment emulsin. The latter has the property in 

 the presence of moisture of decomposing the amygdalin and produc- 

 ing, among other products, hydrocyanic acid and benzaldehyde. 

 These are the important constituents of the essential oil of bitter 

 almonds and should be present in the proportion of from 2 to 4 

 per cent of hydrocyanic acid and not less than 85 per cent of benzal- 

 dehyde. 2 As a matter of fact, most of the commercial oil is below 

 standard as regards the benzaldehyde, owing to the tendency of the 

 latter. to oxidize, forming benzoic acid. 



Almonds are imported with the shells removed, as a rule, since 

 the tariff renders the importation of shelled almonds more profitable 

 than that of almonds in the shell. American-grown almonds, espe- 

 cially the soft-shelled varieties, are usually marketed in the shells, in 

 which case they are sometimes whitened by bleaching. Blanched 

 almonds are prepared by treating the shelled almonds with boiling 

 water, rubbing off the skins, and thoroughly drying them. Almonds 

 are also roasted and salted and sold as burnt and salted almonds. 

 The kernels, either whole or chopped, are used in confectionery, cakes, 

 and similar foods. Almond paste and almond meal are used in 

 making macaroons and biscuits. A fixed oil is obtained from the 

 kernels by pressure, and in the case of bitter almonds the residue is 



1 National Dispensatory, 1905, p. 163. 



2 U. S. Pharmacopoeia, 8th rev., 1907, p. 306. 



