410 POISONS, CONTAGIONS, MIASMS. 



ter IS found to contain free hydrocyanic acid, hydru- 

 ret of benzule (oil of bitter almonds), a peculiar acid 

 and sugar, all substances of which merely the ele- 

 ments existed in the amygdalin. The same decom- 

 position is effected when bitter almonds, which con- 

 Jain the same white matter as the sweet, are rubbed 

 into a powder and moistened with water. Hence it 

 happens that bitter almonds pounded and digested 

 in alcohol, yield no oil of bitter almonds containing 

 hydrocyanic acid, by distillation with water ; for the 

 substance which occasions the formation of those 

 volatile substances, is dissolved by alcohol without 

 change, and is therefore extracted from the pounded 

 almonds. Pounded bitter almonds contain no amyg- 

 dalin, aJso, after having been moistened with water, 

 for that substance is completely decomposed when 

 they are thus treated. 



No volatile compounds can be detected by their 

 smell in the seeds of the Sinapis alba and S. nigra. 

 A fixed oil of a mild taste is obtained from them by 

 pressure, but no trace of a volatile substance. If, 

 however, the seeds are rubbed to a fine powder, and 

 subjected to distillation with water, a volatile oil of 

 a very pungent taste and smell passes over along 

 with the steam. But if, on the contrary, the seeds 

 are treated with alcohol previously to their distilla- 

 tion with water, the residue does not yield a volatile 

 oil. The alcohol contains a crystalline body called 

 sinapin, and several other bodies. These do not 

 possess the characteristic pungency of the oil, but it 

 is by the contact of them with water, and with the 

 albuminous constituents of the seeds, that the vola- 

 tile oil is formed. 



Thus bodies regarded as absolutely indifferent in 

 inorganic chemistry, on account of their possessing 

 no prominent chemical characters, when placed in 

 contact with one another, mutually decompose each 

 other. Their constituents arrange themselves in a 

 peculiar manner, so as to form new combinations ; a 

 complex atom dividing into two or more atoms of 



