XIV.] MUSCLE. 101 



5. The Extractives of Muscle. Prepare Kreatin (C 4 H 9 N 3 2 +H 2 0) 

 omitting the others. 



(a.) Make a strong watery solution of Liebig's extract of meat. Cautiously 

 add lead acetate until precipitation ceases, avoiding excess of the lead. Filter, 

 pass sulphuretted hydrogen through 

 the nitrate to get rid of the lead. 

 A pellicle is very apt to form on the 

 surface. Filter, and evaporate the 

 filtrate to a syrup on a water- bath, 

 and set it aside in a cool place to 

 crystallise. Crystals of kreatin 

 separate out. 



(b.) After several days, when 

 the kreatin has separated, pour FlG - 51- Crystals of Kreatin. 



off the mother-liquor, add to it 5 



volumes of 90 per cent, alcohol to precipitate more kreatin. Filter, wash 

 the crystals with alcohol, redissolve them in boiling water, allow them to 

 recrystillise, and examine them with the microscope (fig. 51). 



Sarkin and xanthin may be prepared from the alcoholic filtrate of (b.). 



The following scheme after Salkowski shows the process of making 

 it from flesh. 



Preparation of Kreatin. 



Minced flesh, digested with water, strained. 



Filtrate heated to Residue, 



boiling, filter. 



Filtrate + lead acetate Residue coagulated 



filter. albumin. 



I 



Filtrate + H 2 S to remove Deposit = phosphate 



lead, filtrate concentrated chloride and sulphate 



= Kreatin. of lead. 



6. Liebig's Extract of Meat. 



(a.) Test it for proteids ; they are absent. 



(b.) Test it for glycogen, doing a control test. It usually con- 

 tains a small quantity. 



(c.) Test it for kreatinin (see "Urine"). Weyl's test usually 

 succeeds. 



(d.) Examine it microscopically ; in addition to a few crystals 

 of common salt, a few clear knife-rest forms, there are numerous 

 crystals of kreatin. 



