248 ROSACEA. 



History — (See also preceding article.) Bitter almonds and their 

 poisonous properties were well known in the antiquity, and used 

 medicinally during the middle ages. Valerius Cordus prescribed them 

 as an ingredient of trochisci.^ 



As early as the beginning of the present century, it was shown by 

 the experiments of Bohm, a pharmaceutical assistant of Berlin, that the 

 aqueous distillate of bitter almonds contains hydrocyanic acid and a 

 peculiar oil which cannot be obtained from sweet almonds. It was 

 then inferred that hydrocyanic acid itself might be poisonous, a fact 

 which, strange to say, had not been noticed by Scheele, when he 

 discovered that acid in 1782, as obtained by distilling potassium 

 ferrocyanate with sulphuric acid. The dangerous action of hydrocyanic 

 was then ascertained in 1802 and 1803 by Schaub and Schrader.^ 



Description — Bitter almonds agree in outward appearance, form, 

 and structure with sweet almonds; they exist under several varieties, 

 but there is none so far as we know that in size and form resembles the 

 long sweet almond of Malaga.^ In general, bitter almonds are of smaller 

 size than sweet. Triturated with water, they afford the same white 

 emulsion as sweet almonds, but it has a strong odour of hydrocyanic 

 acid and a very bitter taste. 



Varieties — These are distinguished in their order of goodness, as 

 French, Sicilian, and Barbary. 



Microscopic Structure — In this respect, no difference between 

 sweet and bitter almonds can be pointed out. If thin slices of the latter 

 are deprived of fat oil by means of benzol, and then kept for some years 

 in glycerin, an abundance of crystals is slowly formed, of what we 

 suppose to be amygdalin. 



Chemical Composition — Bitter almonds, when comminuted and 

 mixed with water, immediately evolve the odour of bitter almond oil. 

 The more generally diffused substances are the same in both kinds of 

 almond, and the fixed oil in particular of the bitter almond is identical 

 with that of the sweet. Bitter almonds however contain on an average 

 a somewhat lower proportion of oil than the sweet. In one instance 

 that has come to our knowledge in which 28 cwt. of bitter almonds were 

 submitted to pressure, the yield of oil was at the rate of 43*6 per cent. 

 Mr. Umney, director of the laboratory of Messrs. Herrings and Co., where 

 large quantities of bitter almonds are submitted to powerful hydraulic 

 pressure, gives 44'2 as the average percentage of oil obtained during the 

 years 1871-2. 



Robiquet and Boutron-Charland in 1830 prepared from bitter almonds 

 a crystalline substance, ATnygdalin, and found that bitter almond oil 

 and hydrocyanic acid can no longer be obtained from bitter almonds, the 

 amygdalin of which has been removed by alcohol. Liebig and Wohler 

 in 1837 showed that it is solely the decomposition of this body (under 

 conditions to be explained presently), that occasions the formation of 



^ Dispensator., Paris, 1548. 336. 337. 343. ' Hence to avoid bitter almonds being 



2 J. B. Richter, Neuere Oegenstdnde der used instead of sweet, the British Pharma- 



C%7/mie,Bre8lau, xi. (1802) 65. J.B. Tromms- copoeia directs that Jordan Almonds alone 



dorflFs Journ. d. Pharm. xi (Leipzig, 1803) shall be employed for Confection of 



262. Preyer, Die Blausdure, Bonn, 1870. Almonds. 



152. 



