n8 



AGRICULTURAL ANALYSIS 



of cases, the quantity of phosphoric acid dissolved is markedly 

 greater than by the methods where no mechanical stirring is 

 employed. 



1 06. Huston's Mechanical Stirrer. The stirring apparatus 

 shown in Fig. 7 differs from those which have heretofore come 

 into use in requiring but a single belt to drive all the stirring rods, 

 and having all the parts protected from the laboratory fumes. 88 

 The details of the belt system are shown in the small diagram in 

 the lower central part of the figure. The apparatus is mounted on 

 a substantial wooden box, 200 centimeters long, 30 centimeters 

 high, and 18 centimeters wide. The driving pulleys, 10 centi- 

 meters in diameter, are enclosed in the upper part of the case. 

 The shafts on which these pulleys are mounted extend through 



Fig. 7. Huston's Mechanical Stirrer. 



the bottom of the enclosing box and carry a wooden disk, n 

 centimeters in diameter, to prevent particles of foreign matter 

 from falling into the beakers. The shafts extend two centimeters 

 below these disks, and to the end of the shafts the bent stirring 

 rods are attached by rubber tubing. 



The board forming the support of the driving pulleys is ex- 

 tended two centimeters in front of the apparatus, and in this 

 extension 12 notches are cut, in which are held the corks carry- 

 ing the tubes which contain the solution to be used in precip- 

 itating the material in the beakers. 



The ends of these tubes are drawn out to a fine point so as to 

 deliver the liquid at the rate of about one drop per second. 



The front of the apparatus is hinged and permits the whole to 

 be closed when not in use, or during the precipitation. 



86 Indiana Agricultural Experiment Station, Bulletin 54, 1895 : 7. 



