442 POISONS : THEIR EFFECTS AND DETECTION. [§§ 545 , 546 . 
parts of cold, and 222 of boiling, water ; in 3-5 parts of cold, and in from 2 to 4 of 
boiling, alcohol. It is with difficulty soluble in ether. It dissolves in concentrated 
sulphuric acid, developing a red-brown colour, which, on the addition of water, 
changes to olive-green. On boiling with dilute acids, it splits up into sugar and 
digitaleretin. 
§ 545. Digitoxin, C 31 H 50 O 10 (according to H. Kiliani, C 34 H 54 O n ), 
is considered the most active poisonous constituent of digitalis leaves ; 
although the experiments of Hans Ziegenbein (Arch. Pharm., 1902) on 
the heart of a frog, with extracts from dried leaves in which the con¬ 
tent of digitoxin was ascertained, show that such extracts are far more 
toxic than could be predicated from the amount of digitoxin found. 
Similar facts may be shown as to muscarine and other extracts containing 
alkaloids ; associated glucosides or, possibly, unknown toxines heighten¬ 
ing the toxic effect. 
§ 546. Separation of Digitoxin from Digitalis Leaves. —Digitoxin 
may be estimated by Keller’s 1 method, which is as follows :—Twenty 
grms. of the powdered leaves are exhausted by percolation with 300 c.c. 
of 70 per cent, alcohol, and the alcohol got rid of by evaporating down in 
a porcelain dish on the water-bath to about 25 grms. ; the residue is 
taken up with water until the weight is brought up to 222 grms. To the 
turbid solution 25 grms. of lead acetate are added, which produce a copious 
precipitate. The thick liquid is transferred to a filter 10 cm. diameter, 
and 132 grms. filtered through. To the clear filtrate, 5 grms. of sodium 
hyposulphite dissolved in 7 grms. of water are added to precipitate the 
excess of lead. The lead precipitate is separated by filtration, 2 c.c. of 
10 per cent, ammonia solution added, and the liquid transferred to a 
separating funnel and shaken out four or five times with chloroform. The 
chloroformic extract is filtered through a double filter previously soaked 
with chloroform, and obtained in this way clear. On distilling the chloro¬ 
form, the digitoxin is obtained as a yellow varnish. It is dissolved in 
3 grms. of chloroform, and precipitated in flocks by 7 grms. of ether 
and 50 grms. petroleum ether. The precipitate is collected in a small 
filter, and washed with petroleum ether. The residue, still moist, is 
dissolved in hot absolute alcohol, the alcoholic solution evaporated, the 
residue treated with 5 c.c. of ether and allowed to evaporate in the 
water-bath ; it now becomes partly crystalline and may be completely 
dried and then weighed. 
Dioscoride Yitali ( Chem . Centr., 1900) isolates digitoxin from the 
tissues by extracting with dilute alcohol, evaporating the alcoholic 
extract to a small bulk ; the residual liquid is treated with lead acetate, 
and then with sodic sulphate to get rid of the excess of lead ; after 
filtration the filtrate is alkalised as in the previous process with ammonia, 
and shaken with chloroform ; the chloroform extract may be treated as 
in Keller’s process. 
1 Zeit. f. anal. Chem., 1900, p. 257. 
