266 ECONOMIC BOTANY. 



color, a peculiar stupefying odor, and a bitter, burning 

 taste. It is heavier than water, and partially soluble in 

 it. Under the microscope it is seen to be partially crystal- 

 lized (the narcotin). In chemical composition it is very 

 complex and variable. It usually contains from nine to 

 twenty-four per cent, of water, and eight per cent, of ash. 

 Of its numerous alkaloids, the most important are mor- 

 phine, papaverin, and narcotin. Its use in medicine is well 

 known. From the seeds a medicinal oil is expressed ; it is 

 yellowish to golden-yellow, and has a specific gravity of 

 .92. It is a drying oil, and dries more readily than flax- 

 seed-oil. The seeds contain from fifty to sixty per cent, of 

 this oil. 



235. The inspissated juice of several species of the 

 genus Aloe (family Amaryllidacem), especially A. vul- 

 garis, A. socotrina, etc., constitutes the drug. Aloes, used 

 in medicine and in dyeing. The plants grow in Africa, 

 have showy, tall, flowering spikes, and thick fleshy leaves, 

 from which, when incisions are made, the juice exudes. 

 Sometimes the leaves are cut ofi" and pressed, or boiled ; 

 and a third mode of obtaining the juice is to sever the 

 leaves close to the ground, and stand them, with the 

 cut ends downwards, in vessels, into which the juice 

 flowSi The juice is boiled down in, shallow pans. The 

 Aloes may be lustrous, of a grayish-yellow color ; and 

 when pulverized light yellow, with no crystals (^Ahe 

 IwAda) ; or blackish or brown, and containing crystals 

 (Aloe hepaiica). The odor is peculiar, reminding of saf- 

 fron; the taste is bitter and unpleasant. Aloin is the 

 active, bitter priuciple. 



236. From Acacia cateehu (family LeguminoscB) is 

 obtained Catechu, or Cfuich, the old name for which is 



