THE URINE. 77 



(c.) Saturate the filtrate with crystals of sodic chloride or 

 ammonium chloride. The myosin is precipitated. 



(d.) Collect some of the precipitate of 4 (c.), dissolve it with 

 a weak solution of common salt, and test for proteid reactions 

 (Lesson I., 1). Repeat 3 (c.) 



5. The Extractives of Muscle. Prepare Creatin, 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 filtrate 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 creatin 

 separate out. 



(6.) After several days, when the creatin has separated, 

 pour off the mother liquor, add to it 5 volumes of 90 per 

 cent, alcohol to precipitate more creatin. Filter, wash the 

 crystals with alcohol, redissolve them in a boiling < water, 

 allow them to recrystallise, and examine them with the 

 microscope. 



Sarkin and xanthin may be prepared from the alcoholic filtrate 

 of (6.) 



LESSON XIII. 



THE URINE. 



1. The Urine is a transparent light straw or amber-coloured 

 watery secretion derived from the kidneys, containing nitro- 

 genous matters, salts, and gases : it has a peculiar odour, bitter 

 saltish taste, and acid reaction. 



(a.) Evaporate a drop of urine on platinum foil. Do this 

 over the flame of a Bunsen burner, taking care not to burn 

 it. A brownish-yellow stain, with an ammoniacal odour, is 

 obtained. 



