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or less impure, is to be agitated with oil of vitriol (half its own 

 volume will be sufficient), and allowed to remain in contact with the 

 acid ; of course in a clean, dry, stoppered bottle, and with occasional 

 agitation, till the acid no longer becomes darker in colour. As long 

 as the action is incomplete there will be seen, after rest at the lino 

 of contact, a darker ring. When this no longer appears, the chlo- 

 roform may be drawn off, and, for greater security, once more acted 

 on by a quarter of its volume of the acid, which should now remain 

 colourless. It is now to be once more di'awn off, and, in a dry 

 stoppered bottle, mixed with a little powdered peroxide of manganese, 

 with which it is gently agitated and left in contact, until the odour 

 of sulphurous acid is entirely destroyed, and the chloroform has 

 acquired a mild agreeable fruity smell. It has then only to be 

 poured off into a proper phial. It will now leave no disagreeable 

 smell when evaporated on the hand. (If the commercial chloro- 

 form, after having hQen frequently well shaken, and left for some 

 time in contact with the acid, has given only a moderate tinge of 

 colour to it, it is probable that it may be completely purified by that 

 first process. To ascertain this, test a small portion in a tube with 

 fresh acid, shaking well, and allowing it to stand some time. If it 

 do not colour the acid at all, then the whole chloroform has only to 

 be finally purified by the oxide of manganese. If the acid become 

 coloured in the test tube, it will be as well to act on the whole chlo- 

 roform a second time with fresh acid, till it stands the test. Mr 

 Kemp has observed, in repeating this process for me, the very 

 curious fact that, as soon as the action is complete and the oily im- 

 purities are destroyed, but not sooner, the chloroform tested with the 

 acid in a tube exhibits a strongly convex surface downwards, where 

 it rests on the pure acid, or, what is the same thing, the acid becomes 

 concave at its upper surface. The smallest trace of impurity, not 

 sufficient to affect the density of the chloroform, we have found to 

 render the line of junction horizontal. It is probable that this may 

 become a valuable test of the perfect purity of chloroform, but 

 we shall not say more on this subject until wc have thoroughly 

 examined it.) 



This process requires no apparatus beyond a few stoppered bottles, 

 and a syphon, or a pipette, if we wish to draw off the whole chloro- 

 form without loss. The use of the oxide of manganese is due to Mr 

 Kemp ; and, on the large scale, the chloroform may be filtered 



