No. 644] SHORTER ARTICLES AND DISCUSSION 285 



to filter into the vessel on the base of the stand. It is necessary, 

 at approximately fifteen-minute intervals, to thrust into the 

 burette, as far down as the shoulder, or point of taper (just 

 above the rubber tube on which the pinch cock rides), a straight 



7^ P FIG. 2. Pipette with flattened 



copper wire rod, holding in its lower end a bit of cotton. This 

 serves to stir up the material which it is desired shall be de- 

 posited upon the filter paper, to prevent it from settling and 

 adhering to the sides of the glass, on the slopes of the taper. 



