CASSIA. 211 
The following is a description of a simple practical process re- 
commended for estimating the rectification residue of a sample :— 
“ Weigh out about 50 grammes of the oil into the small fraction 
retort a, connect it with the cooling-tube 4, and place the thermo- 
meter c, by means of a perforated cork, in such a manner as the 
bulb of the thermometer stands about 5 or 10 centimétres above 
the fluid. The retort may not be more than half full. 
Fig. 8. 
= 
ammo eae ere 
————————— 
= = 
es 
‘To prevent bursting, the heat must be applied by degrees. For 
this purpose the flame of a Bunsen-burner or of a spirit-lamp must 
be moved to and fro underneath the retort. At first some water 
escapes with a crackling noise from the fluid. Usually the oil 
commences to boil at about 200°, and then the thermometer rises 
quickly to 240°. The bulk of the oil distils over between 240° 
_ and 260°. At last, white vapours develop in the retort, the ther- 
mometer rising at the same time from 280° to 290°. When this 
takes place, the distillation is to be interrupted; the residue is 
allowed to cool in the retort and is weighed with it. (The retort 
P2 
