166-168] Analysis of the Crude Fibre 109 



166. Insoluble Ash. — Weigh out 2 grams of dry crude 

 fibre in a platinum dish, and determine the ash as before. 



167. Calculation. — First calculate from the weights of 

 different substances the following percentages : 



Percentage of moisture 



„ woody fibre \ in the sample ; 



„ crude fibre J 



„ total nitrogen \ 



„ albuminoid nitrogen [• in the dry matter ; 



„ ash J 



° I in the crude fibre. 



,, ash ) 



Work out the percentages of albuminoids contained in the 

 dry matter and crude fibre respectively by multiplying the per- 

 centages of albuminoid nitrogen by 6*25. 



Reduce all the percentages to parts per hundred of the 

 total sample, thus : 



percentage of ash in dry matter x percentage of dry matter 



100 



= percentage of ash in sample. 



Likewise 



percentage of ash in crude fibre x percentage of crude fibre 



100 



= percentage of insoluble ash in sample. 



Make the following additions and subtractions : 



Total nitrogen — albuminoid nitrogen = amide N ; 

 Total albuminoids — insoluble albuminoids = soluble albuminoids ; 

 Total ash — insoluble ash = soluble ash ; 



Crude fibre — (insoluble albuminoids + woody fibre + insoluble ash) 

 — digestible fibre. 



168. The following figures, taken from actual analyses of 

 grass and hay, show the method of entering results. 



