9 8 



Analysis of Feeding Materials 



[143 



in the beaker is decanted through this linen. The solid 

 matter on the linen is washed back into the beaker with hot 

 water. Fifty c.c. of 5 per cent. KHO solution are added, and 

 then water up to the 126-c.c. mark. The beaker is returned 

 to the burner and the liquor boiled for half-an-hour, filled with 

 cold water, and allowed to stand as before. 



The remaining solid matter, which contains only woody 

 fibre and sand, is filtered off by means of the linen and well 



washed : firstly, three 

 times with hot water ; 

 secondly, once with di- 

 lute HC1; thirdly, three 

 times with hot water; 

 and, lastly, twice with al- 

 cohol. 



Filtration may be very 

 much hastened by draw- 

 ing the linen tightly over 

 the edges of the pot, as shown in fig. 39. This causes a 

 partial vacuum below, and the pressure of the air above forces 



the liquid through the 

 cloth. 



The next operation is 

 to transfer the fibre to a 

 weighed porcelain capsule, 

 which requires some little 

 dexterity. 



As much of the alco- 

 hol as possible is squeezed 

 out, and the cloth is 

 stretched on a tile, holding it as in fig. 40. The fibre is 

 removed with the tip of a steel spatula and placed in the 

 weighed capsule, care being taken to scrape all the substance 



Fig. 39. 



Fig. 40. 



