§ 1 67. AMYGDALIN ; ESTIMA TION. 1 65 



barium salt formed, whilst from the latter only one of -the former 

 can be obtained for every two of the latter, i 



Methods for the guamtitative estimation of amygdalin have 

 been proposed by Rieckher ^ and Peldhaus.' That of the latter 

 is ba ^ed upon the decomposition of the amygdalin by emulsin in 

 aqueous solution and estimation of the, hydrocyanic acid produced. 

 Almonds are freed from oil, powdered and macerated with water 

 for twenty-four hours.. The hydrocyanic acid is then distilled off 

 in a current of steam, received in ammoniacal water, and estimated 

 as cyanide of silver. Anyone that has distilled bitter-almond 

 water, or brought hydrocyanic acid. into" contact with powerful 

 alkalies, will know that this method is very faulty. To obtain 

 even approximate results I think it must be necessary that (a) the 

 flasks in which the maceration is conducted should be completely 

 filled with the mixture, and (b) the use of ammonia or other 

 powerful base should be avoided. 



In Rieckher's. method the amygdalin i^ decomposed by hydrate 

 of baiium, a reaction which, according to Lehmann, takes place 

 tolerably smoothly. One reason for preferring this process to Feld- 

 haus's is, that the result can be checked by estimating on the one 

 hand the ammonia liberated^ and "on the other the amygdalate of 

 barium produced. The latter can be determined in the solution 

 after expulsion of the ammonia by removing the excess of barium 

 with carbonic acid gas, and then decomposing with sulphuric acid 

 the amygdalate of that metal which has been left in solution. 

 From the sulphate of barium thus obtained the amount of amyg- 

 dalin acted upon can be calculated. This method cannot^ how- 

 ever, I think, be applied directly to almond meal deprived of fat, 

 but only to the impure amygdalin obtained by exhausting with 

 boiling alcohol and precipitating with ether. 



Myronate of potassium crystallizes in rliombic prisms, which are 

 freely soluble in water; sparingly in cold -alcohol, but are dissolved 

 by warm (50° to 60°) 85 per cent, spirit. Myronic acid itself is also 

 soluble in cold strong. spirit, but rapidly decomposes. In aqueous 

 sol'y.tion myronate of potassium is easily resolved by ferments, 

 especially by the myrosin of white and black mustard (but not, 



^ It is remarkarble that Lehmann could find cane-sngar in the seeds of the 

 apple, pear, cherry, plum, peach, and bitter almond, which contain ' crystals 

 lizable amygdalin, whilst sweet almonds yiel4ed glucose only. 



' N, Jabrb. f. Fharm. xxiv. 65. * Archiv d. Pharm. dxvi. 52. 



