440 PRACTICAL PHYSIOLOGY 



ether should be used to fill the Soxhlet one and a half times, and it 

 should be made to siphon over at least twelve times. 



(4) The Percentage of Sugar. Ten c.c. milk are mixed with twice 

 that amount of alcohol (meth. spt.) so as to precipitate all the proteid, 

 which is then filtered off. The precipitate is thoroughly washed with 

 alcohol, and the washings are added to the filtrate. Filtrate 

 and washings are then placed on the water-bath till all the 

 alcohol has evaporated. The contents of the evaporating basin are 

 then carefully washed into a 100 c.c. measuring cylinder, and the 

 volume made up to 100 c.c. This is then placed in a burette and 

 titrated with boiling Fehling's solution as described on p. 274. Ten c.e. 

 Fehling's solution correspond to 0-0676 g. lactose, therefore the number 

 of c.c.'s of the diluted extract required contains 0'0676 gr. lactose. In 

 order to calculate the percentage it must be remembered, that each 

 c.c. of the solution in the burette corresponds to 0*1 c.c. of the original 

 milk. 



(5) The Percentage of Ash. A weighed quantity of milk is 

 evaporated to dryness on a water bath in a weighed crucible. The 

 crucible is carefully heated over a free flame until a perfectly dry 

 and black ash has been obtained. The flame is now strengthened and 

 the ash is heated until it becomes white. The crucible is then allowed 

 to cool in a desiccator, after which it is weighed. 



CHAPTER VI. 

 MUSCLE. 



The Extractives of Muscle. The most important of these are 

 Creatin, Hypoxanthin and Xanthin ("alloxuric bodies"), and sarco- 

 lactic acid. They can be separated from the same muscle extract 

 by the following procedure : 



500 grammes of meat, from which as much fat and tendon as possible 

 have been removed, are passed through a mincing machine; the mince 

 is stirred up with 500 c.c. water in a large evaporating dish or 

 enamelled basin, and heated on a water bath to about 55 C., for about 

 half an hour. The extract is strained through muslin, and the 

 residue extracted several times in a similar manner, the extracts 

 being, mixed together. The proteid in this extract is then coagulated 

 by boiling and, after cooling, the coagulum is removed by filtra- 

 tion, So far the preparation of the extract should be carried out 





