184 MATERIA MEDIC A AND THERAPEUTICS. 



is found in cakes, either large and irregular, or small and 

 lenticular, covered with a poppy leaf, and marked with its mid- 

 rib, but without rumex seeds. It smells much less strongly 

 than Smyrna opium. Besides the two officinal varieties, there 

 are found in the market Egyptian opium, in round flattened 

 cakes of a reddish hue, with vestiges of a leaf ; Persian opium 

 in sticks or lumps ; Indian opium in balls, enveloped in poppy 

 leaves, or in cakes ; and French and English varieties. 



Impurities (chiefly adulterations). Opium is often soft 

 from excess of water, which causes great variation in the 

 strength. Stones, fruits, leaves, etc., may be detected by 

 filtering a decoction ; and starch by the iodine test. The 

 officinal test is intended to ascertain the amount of morphia in 

 specimens which are pure but of doubtful richness. 



Composition. Opium contains (1) certain alkaloids ; (2) two 

 neutral substances ; (3) two organic acids ; (4) water, resin, gum, 

 extractives, odorous principles, and other constituents of plants. 

 The important components are as follows : 



General chemical characters. Reactions, and Incompatibles. A 

 fluid (watery or spirituous) preparation of opium reddens litmus 



