142 RESINS, BITTER PRINCIPLES, ETC. 



remains dissolved in the mother-liquor and washings may be 

 removed by shaking with chloroform. 



Santonin is almost insoluble in cold water, but is dissolved by 

 ether, alkalies and boiling alcohol. It melts at 169, turns yellow 

 on exposure to light, produces no colouration when dissolved in 

 cone, sulphuric acid, but colours alcoholic potash transiently 

 carmine. If a solution of santonin in sulphuric acid is heated to 

 150, and a drop of a dilute solution of ferric chloride subse- 

 quently added, the mixture assumes a red tinge, gradually chang- 

 ing to violet. 



155. Picfrotoxin, etc. Amongst other substances to be looked 

 for in the ethereal extract the following may be mentioned : 



Picrotoxin. Soluble in 150 parts of cold, and 25 of boiling 

 water, as well as in alcohol, chloroform, and amylic alcohol. 

 From aqueous solution ( 55) it may be extracted by the last two 

 solvents, and also by ether, but not by benzene. 1 It crystallizes 

 with facility from water and alcohol in four-sided prisms, reduces 

 alkaline copper solution, and dissolves yellow in cone, sulphuric 

 acid. If dry picrotoxin is mixed with 6 parts of nitrate of potash, 

 and sufficient cone, sulphuric acid to form a pasty mass, a brick- 

 red colour is developed on adding a solution of soda (1 to 3) in 

 excess. The reaction succeeds better if the picrotoxin is moistened 

 with nitric acid, dried on the water-bath, mixed with a very 

 little sulphuric acid, and then with solution of soda. 



Digitalin. According to Schmiedeberg, 2 this glucoside is in- 

 soluble in water and dilute soda, but soluble in warm dilute acetic 

 acid. Alcohol, alone or mixed with chloroform, dissolves it easily, 

 but in pure ether or chloroform it is more sparingly soluble. It 

 is a colourless crystalline glucoside, yielding glucose and digita- 

 liresin by decomposition with hydrochloric acid in alcoholic soli 

 tion. It dissolves yellowish green in boiling hydrochloric acid, 

 brown in sulphuric acid, the latter solution becoming violet on 

 the addition of bromine water ( 55). 



Digitoxin accompanies digitalin in foxglove ; it crystallizes in 

 pearly plates and needles, is not very soluble in ether, am 

 insoluble in water and benzene. Chloroform and hot alcohol 



1 See also Gaabe, 'Unters iiber einige Derivate des Picrotoxins.' Diss. 

 Dorpat, 1872. 



2 Archiv f. exper. Patholog. und Pharm. iii. 16, 1874 (Pharm. Journ. and 

 Trans. [3], v. 741). 



