232 THE JOURNAL OF PHARMACOLOGY. 



son exists, as far as we know, why we should not use Curaeoa aloes to the 

 exclusion of the Socotrine, especially as it costs only about one-eighth as 

 much. So much for the commercial side of aloes. 



T. and H. Smith in 1851, and Stenhouse, Fliickiger, Tilden, E. Schmidt, 

 Liebelt and Groenewald since have studied aloes as to the aloin obtained 

 therefrom. The Smiths operated on Barbadoes aloes, and obtained what 

 they called barbaloin, formula C t 7 H 18 7 + H 2 0. Fliickiger, in 1871, 

 decided that the aloin he and Histed obtained from Socotrine aloes was 

 not, as Pareira had stated, identical with barbaloin, but was C 15 H 16 7 . 

 From these aloins, notably barbaloin, Tilden had obtained, by the action 

 of strong oxidizing agents such as potassium bichromate, alaxanthin or 

 methyltetra-oxyanthraquinone, thus indicating that aloin was a derivative 

 of anthraquinone. As we all know, aloes contains besides the aloin, quite 

 a quantity of resin, which has, however, as yet not been investigated. 

 Tschirch and his pupils at Bern have been these past four or five years 

 investigating in order the various resins, beginning with tolu, benzoin, 

 peru, etc. He has recently taken up the resin of aloes, and finds it to be 

 like the other resins, an ester or organic salt, made up in case of Barba- 

 does aloes of cinnamic acid, and one of that peculiar and characteristic 

 class of resin alcohols, which he finds in all resins and has named resino- 

 tannols and which he has named aloresiuotannol. It is a gray-brown 

 powder of formula C 22 H 26 6 , and contains two hydroxyl groups, as he 

 obtained from it a di-benzoyl derivative. The resin of Cape aloes was 

 similarly treated, and yielded the same aloresinotaunol; but to demon- 

 strate that the resin was different from that of Barbadoes aloes, he found 

 that the acid in combination with it was not cinnamic but paracumaric 

 acid. 



The resin of Socotrine aloes has not been taken up as yet, but the aloin 

 from the three aloes was next considered. Here some most unexpected, 

 valuable and interesting observations were made, and as the result of close 

 observation of a certain color reaction of aloe, known as Borntraeger's 

 tests for aloes. It is this : aloes or aloes solutions, when treated with 

 either benzin or benzene, yield to these solvents a yellow substance' which 

 turns cherry-red on the addition of ammonia. It was noticed that Cape, 

 Barbadoes and Curaeoa aloes gave the reaction, while Natal and liquid or 

 true Socotrine aloes did not. The color was not due to the aloin or to the 

 resin, as both of these, when pure, did not give it, but to another substance 

 which no one ever thought was contained in aloes, and which was ob- 

 tained from the latter, or from aloin obtained from the first three kinds of 

 aloes just mentioned. It is emodin, the great laxative, to which rhubarb, 

 senna, cascara, and frangula, owe their laxative properties. It can be ob- 

 tained from aloin by extracting this with ether, from which it will crystal- 

 lize, and can be purified by sublimation. Hence the so-called Born- 



