342 BUHACHIRO TASAKI AND USHIO TANAKA. 
strong toxic action, for Guinea pigs die after a dose of 0.03 9m. per 1 kile. 
bod y weight. 
Material Animal Weight | Method of administration | Dosis Result 
if Guinea pig 250) Intravenously 0.02 Exitus (strong reaction). 
bk A ” j “= > nn (middle N 
II es 330 35 0.0165 = (strong ieee 
+ 7 290 ee 0.02 ae der RM): 
As above mentioned, the toxic constituents are not extracted with ether 
or alcohol, but chiefly with water, and the fraction which is soluble in dilute 
acetic acid but not in alcohol is more powerful than the other. The name 
robitin was given to this substance. 
II. PREPARATION OF ROBITIN. 
The air-dried bark is shaken with 10 parts of distilled water. The ex- 
traction is twice repeated and the combined extract filtered roughly through 
linen cloth. The residue is pressed and its sap is also added to the filtrate. 
The turbid and slightly yellowish brown filtrate thus prepared is heated for 
30 minutes at a temperature of 80 to 90°C. and then filtered to a transparent, 
reddish brown liquid. When we cencentrated this filtrate to one tenth of its 
volume under a pressure of 20mm. at a temperature not higher than 40°C., 
a saturated solution of lead acetate was added until no more precipitate occur- 
red. After filtering the precipitate of impurities and separating the excess of 
lead with sulphuretted hydrogen gas, the filtrate is again condensed to one 
twentieth of the first volume under similar conditions. When the concentrated 
reddish brown extract is slowly poured into a large quantity of absolute 
alcohol, white flock is abundantly precipitated. After letting it stand for a 
night, the precipitate is sucked, washed twice with absolute alcohol and desic- 
eated in vacuum over calcium chloride. The quantity of robitin thus prepared 
amounts to 3% of the air dried material. 
From the liquid in which robitin was collected, we obtained a large 
quantity of crystals of certain potassium salts and its reddish brown mother 
liquor docs not react on animals. 
