AL′OIN

(-o-ĭn). C 17 H 18 O 7 . [Eng., Fr.] Syn. Al′öin ; Aloï′na , L. The Me rs T. & H. Smith, of Edinburgh, have applied this name to a crystalline substance, which they a ert to be the pure cathartic principle of aloes. Their proce is to evaporate to the consistence of a syrup, in vacuo, a solution obtained by exhausting a mixture of aloes and sand, with cold water, and then to set it aside for a few days. The resulting dark crystalline ma is purified by pre ure between folds of bibulous paper, and repeated crystallisation from hot water. Barb a does aloes are commonly used for the purpose; but soft or semi-liquid Socotrine aloes, or the une vapor a ted Socotrine-aloes juice, is probably its best source. Tilden gives the following proce for the preparation of aloin:—The aloes crushed small is to be di olved in nine or ten times its weight of boiling water acidified with sulphuric acid. After cooling and standing for a few hours, the clear liquid is decanted from the resin, and evaporated. The concentrated solution deposits a ma of yellow crystals, which can be purified by washing, pre ure, and recrystallisation from hot spirit. After several recrystallisations the aloin is obtained in the form of beautiful yellow needles, which are pretty soluble in water and in alcohol, but soluble with difficulty in ether.— Dose , 1 to 2 gr.