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PROCEEDINGS OF THE AMERICAN ACADEMY 



without difficulty upon ignition, and nitric and acetic acids are suit- 

 able agents, therefore, for the liberation of boric acid previous to 

 distillation. 



The actual distillation presented at first some difficulty, — for the 

 repeated, thorough, and rapid evaporation of a liquid charged with 

 soluble or insoluble solid matter is apt to involve some mechanical 

 transfer to the distillate of material which should remain in the resi- 

 due, — but the device of the following description solves the problem 

 successfully. 



The apparatus, which is shown in the accompanying cut, consists 

 essentially of a retort, condenser, and bath for heating. For the last 

 I have used a paraffine bath, as being on the whole the most con- 

 venient. The condenser is set vertically, to facilitate changing the 

 level of the retort within the bath, and to secure at the same time 

 continual and thorough washing of the tube by its own condensations. 

 The retort, somewhat like the well-known drying tube of Liebig in 

 general shape, is easily made of a pipette by bending the tube at one 

 end to a right angle, at the other to a goose-neck, as shown. To the 



