§ 1G7. AMYGDALIN; ESTIMATION. 1G5 



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

 can he obtained for every two of the latter.^ 



Methods for the iiuaidiiative estimation of amygxlalin have 

 been proposed by Rieckher ^ and Feldbaus.^ That of the latter 

 is based upon the decomposition of the am3gdalin 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 oft' 

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

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

 waterj or brought hydrocyanic acid into contact with powerful 

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

 even approximate resiüts I think it must be necessary that {a) the 

 flasks in which the maceration is conducted should he. completely 

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

 powerful base should be avoided. 



In Itieckher's method the amygdalin is decomposed by hydrate 

 of barium, 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 liy estimating on the one 

 hand the ammonia lilierated, and on the other the amygdalate of 

 barium produced. The latter can l)e determined in the solution 

 after expulsion of the ammonia by remo^■ing the excess of barium 

 with carbonic acid gas, and then decomposing with sulphuric acid 

 the amygdalate of that metal which has l^een 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 potasüum crystallizes in rhombic 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 

 solution myronate of potassium is easily resolved by ferments, 

 especially by the myrosin of white and Ijlack mustard (Ijut not 



1 It is remarkable that Lehmann could find cane-sugar in the seeds of the 

 upple, pear, cherry, plum, peach, and bitter almond, which contain crystal- 

 lizable amygdalin, whilst sweet almonds yielded glucose only. 



^ N. Jahrb. f. Pharm, xxiv. 65, ^ Archiv d. Pharm, clxvi. 52. 



