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PROCEEDINGS OP THE AMERICAN ACADEMY. 



is very inexpensive, aud it occupies but little space. Each student may 

 possess a complete set of apparatus, and every one knows the value from 

 a pedagogic standpoint of such a possibility. A further advantage lies 

 in the fact that the pipette is easy to fill and to clean ; and a precipitate 

 in the liquid is not apt to clog its working. The short straight capillary 

 brings an obvious gain of speed in transferring. Moreover, because of 

 this speed, and the fact that the pressure during transference is always 

 from the outside inward, the danger of loss by leakage is considerably less 

 than it is with Hempel's apparatus. It is well known that in a rubber 

 tube an internal pressure may cause leakage, while an external pressure 

 tends to stop small outlets by causing the rubber tube to be pressed more 

 closely together. 



On the other hand, the calculation is less obvious, because the volume 

 taken is not just a hundred cubic centimeters ; and somewhat more care 

 must be used to prevent the access of air into the pipette from below 

 while shaking. A little practice enables one to shake thoroughly the 

 liquid in the bulb without much agitation in the bottle if the movement is 

 hinged about the point D ; hence the danger is slight. Another slight 

 difficulty is the possible leakage of the absorbent around the stopper of 

 the pipette bottle, — an unpleasant occurrence which has no effect upon 

 the accuracy of the method. 



In presenting for general use any new instrument one must record its 

 practical working in the laboratory. Everybody knows that plausible 



Analysis of known Mixtures of Air and Carbon Dioxide. 



