PANCREATIC DIGESTION". 97 



filtered out and the albumose reactions tried. The filtrate 

 from the albumoses contains the peptones. Try the biuret 

 test which should give a pink color. On account of the 

 presence of ammonium sulphate a large excess of the alkali 

 must be employed ; it may be more convenient to add this 

 in the solid form. 



Let the remainder of the original solution digest for 

 a week in the presence of thymol or chloroform as a pre- 

 ventive of putrefaction,, then concentrate the solution to a 

 small bulk and precipitate the albuminous compounds from 

 it by the addition of about twice the volume of alcohol. 

 Filter these off and evaporate the alcohol., or distill it if 

 there is a large quantity. Concentrate the liquid on the 

 water-bath to a thin syrup, then let it stand until the 

 tyrosin crystallizes out. Examine the form of the crystals 

 under the microscope. If there is enough of the liquid to 

 filter, remove the tyrosin and let the leucin crystallize 

 from the filtrate. If there is only a small amount they 

 can both be identified with the microscope. Sketch these 

 and hand in the results. If there is a sufficient quantity 

 they may be tested by the reactions given in Experiments . 

 217-222. Eecrystallization often gives better crystals. 



Steapsin, the second ferment of the pancreatic juice, 

 splits the fats into glycerin and the fatty acid with which 

 it was united. In the process of digestion, as it goes on 

 in the animal body, only a part of the fat is thus decom- 

 posed. The acid which has been set free in this manner 

 unites with the carbonate of sodium which is present in the 

 intestine, forming the sodium salt (a soap), and this serves 

 to emulsify the rest of the fats by surrounding the globules 

 with such a coating that they are not able to unite into a 

 large mass. The sodium carbonate is not able to decompose 

 the fat-molecule or to form a soap with the acid until the 



