THE FMCES. 213 



evaporated in a light weighed Erlenmeyer flask, the last 

 traces of ether driven out by means of a current of air or C0 2 , 

 and the flask heated for several hours at 80 or for a 

 short time at 105 and weighed. If it is desired to know 

 also the quantity of the fatty acids present in the form of 

 soap, moisten a few grams of the material, accurately weighed, 

 in a dish with dilute hydrochloric acid (1.3), dry on the water- 

 bath, transfer the residue completely to the Soxhlet thimble, 

 by wiping out the dish with pieces of filter-paper and placing 

 these also in the thimble, and extract with ether. More 

 ether extract will be obtained than in the first determina- 

 tion. The excess is due to the fatty acids present in the form 

 of salts. If the residue has a brown color, it is better to 

 -extract it once more with ether. If the quantity of the 

 faeces is small, the powder which has already been extracted 

 with ether may be used for the determination of the fatty 

 acids, or, if only a total determination of the fat and fatty 

 acids is desired, the powder may be dampened with hydro- 

 chloric acid and dried on the water-bath before the extrac- 

 tion. 



5. Determination of the Starch or of the Carbohydrates 

 according to Marker. Place between 3 and 4 grams of the 

 material (accurately weighed) in a porcelain vessel (the pots 

 in which Liebig's extract of beef is packed are very suitable), 

 pour on 25 cc. of a 1 per cent, solution of lactic acid and 30 

 cc. of water, s.tir thoroughly with a glass rod, rinse this off 

 with the smallest possible quantity of water, and heat in an 

 autoclave for two and one-half hours at three atmospheres 

 pressure. By this means the starch will be converted into 

 dextrin, while the cellulose will not be attacked. When 

 there is no longer any pressure in the autoclave, it is opened, 

 the contents of the porcelain vessel, together with the sus- 

 pended matter, are placed in a 250-cc. measuring-flask, rins- 

 ing; the vessel well with water and, when perfectly cold, the 



