220 



PHYSIOLOGICAL CHEMISTRY 



PART II 

 MANIPULATION OF THE RESIDUE 



Evaporate, filter, and extract with ether. 

 ~~~ I 



Ether Extract. 



Evaporate, extract the residue with 

 warm water, and filter. 



Filtrate No. 2. 



Contains oxyacids and 

 skatole-carbonic acid. 



Aqueous Solution. 



Evaporate until crystals begin to 

 form. Stand in a cold place until 

 crystallization is complete. Filter. 







Crystalline Deposit. 

 Consists of a mixture of 

 leucine and tyro sine crystals 

 (Figs. 25, 28 and 154, pages 

 75, 79 and 492.) 



I 



Filtrate No. i. 



Contains protease, peptone, 

 aromatic acids, and trypto- 

 phane. 



Residue. 



Contains non-volatile 

 fatty acids. 



DETAILED DIRECTIONS FOR MAKING THE 



SEPARATIONS INDICATED IN 



THE SCHEME 



Preliminary Ether Extraction. This extraction may be conducted in a separately 

 funnel. In order to make a satisfactory extraction the mixture should be shaken 

 thoroughly. Separate the ethereal solution from the aqueous portion and treat 

 them according to the directions given on page 218. 



Ether Extract. Evaporate this solution on a safety water-bath until the ether 

 has been entirely removed. Extract the residue with warm water and filter. 



Aqueotfs Solution. Evaporate this solution until crystallization begins. Stand 

 the solution in a cold place until no more crystals form. This crystalline mass con- 

 sists of impure leucine and tyrosine. Filter off the crystals. 



Crystalline Deposit. Examine the crystals under the microscope and compare 

 them with those reproduced in Figs. 25, 28, and 145, pages 75, 79, and 480. Do the 

 forms of the crystals of leucine and tyrosine resemble those previously examined? 

 Make a separation of the leucine and tyrosine and apply typical tests according to 

 directions given on pages 85 and 86. 



Filtrate No. i Make a test for tryptophane with bromine water (see page 192), 

 and also with the Hopkins-Cole reagent (see page 98). Use the remainder of the 

 filtrate for the separation of proteoses and peptones. Make the separation ac- 

 cording to the directions given on page 119. 



Filtrate No. 2. This solution contains para-oxyphenylacetic acid, para-oxy- 

 phenylpropionic acid and skatole-carbonic acid. Prove the presence of these 

 bodies by appropriate tests. Tests for oxyacids and skatole-carbonic acid are 

 given on page 223. 



