III. 



ANALYSIS OF THE F^CES. 



The faeces, advantageously collected in a weighed dish 

 (weighed with a glass rod for stirring), are dried by long-con- 

 tinued heating on a water-bath, stirring frequently with the 

 glass rod, until they appear dry enough to powder. The 

 drying may be facilitated, according to Poda, 1 by repeatedly 

 pouring on absolute alcohol (after four to six hours add 50 cc. 

 of absolute alcohol, then after another hour 25 cc., and heat 

 again). Weigh the dish and determine thus the weight of 

 the air-dried faBces. These are then quickly powdered and 

 preserved in a well-closed, glass-stoppered bottle. The loss 

 due to the removal of the contents of the dish and powdering 

 makes no difference. 



1. Determination of the Amount of Water. Weigh about 

 1.5 to 2 g. in a cork- or glass-stoppered weighing-tube 

 (10 to 15 cm. long) whose weight is known to a centigram, 

 shake out the contents of the tube into a weighed platinum 

 dish, weigh the tube again, and thus determine the weight 

 of the quantity used. Heat at 110 until the weight is con- 

 stant. When required the amount of water may be calcu- 

 lated from the moist substance. 



2. The Determination of the Ash is made with the same 

 material. Heat the residue obtained in the determina- 

 tion of water cautiously until it ceases to give off vapor, 



1 Zeitschr. f. physiol. Chem. 25, 355. 



211 



