ALOES 93 



bitterness on standing, the aloin being replaced in part at least by a 

 sugar aloinose, which forms yellow crystals that are colored red and 

 then green with concentrated hydrochloric acid and orcin. Aloin is 

 considered by some to be an emodin-glucoside which on oxidation 

 splits off emodin, the latter on further oxidation forming rhein. 



Stacy uses a freshly made solution of potassium ferri-cyanide 

 which is added to the cold aqueous solution of aloes. This reagent 

 gives a pink color for Barbadoes aloes in dilutions of 1 part in 10,000. 

 Cape and Socotrine aloes give an emerald-green color as also does 

 aloin. Extracts of cascara and rhubarb give no reaction. (The 

 Analyst, 1916, p. 75.) 



Adulterants. Aloes formerly contained various mechanical 

 impurities, and this was the reason for the introduction of a purified 

 aloes into the U. S. Pharmacopoeia. As heat impairs the quality of 

 the aloes and as the requirements forbid adulteration the untreated 

 aloes should be employed. The aloin is sometimes removed, as in 

 the Curasao aloes, when it has the appearance of Cape aloes and is 

 sometimes sold for it. Recently aloes has been coming into market 

 packed in thin layers separated by paper. 



Allied Plants. Natal Aloes is a hepatic variety of aloes which 

 was at one time exported from Natal, the botanical origin being 

 unknown. It occurs in grayish-brown or greenish-black, dull, opaque 

 masses, often covered with a brownish powder. The odor somewhat 

 resembles that of Cape aloes. The powder is grayish-green or pale 

 yellowish-brown and microcrystalline, giving a permanent crimson 

 color with nitric acid and a deep blue with sulphuric acid and vapor of 

 nitric acid. The latter test serves to distinguish this aloes from all 

 the other varieties. The drug contains aloin (nataloin), but not 

 emodin. Both Natal aloes and nataloin are physiologically inactive. 



Jaffarabad Aloes is a vitreous variety obtained from the East 

 Indies and is exported from Bombay. It occurs in circular, flat- 

 tened cakes, of a deep black color externally, and with a black, glossy, 

 slightly porous or somewhat laminated fracture. It yields 13 to 20 

 per cent of aloin, which is apparently chiefly barbaloin, and gives a 

 deep crimson color with nitric acid. 



Detection of Aloes in Mixtures. According to Mossier (Pharm. 

 Post, 1913, 46, 313, 325), the following method may be used for the 

 detection of aloes in mixtures containing cascara, rhubarb, senna, etc. 

 The extract, etc., is evaporated to drive off alcohol and the residue 

 dissolved in water. The filtered solution is heated with 10 cc. of 

 normal sulphuric acid for thirty minutes on the water-bath. The 

 sulphuric acid is then exactly precipitated with barium hydroxide 



