164 LAB OR A TOR Y G UWE IN PHYSIOLOG Y. 



This test is usually given as a universal proteid test. 

 Tabulate results on the above suggested series (a)-(g) 

 noting any variations of the reaction in the different 

 proteids. Besides variations in the reaction with dif- 

 ferent proteids there are marked variations with differ- 

 ent strengths of sol-ution of the same proteid. 



(4) A general test for proteids is to heat a proteid-con- 

 taining liquid with half its volume of Millorts reagent. 

 A precipitate appears which is yellowish at first but 

 turns red under the influence of heat. Test each of 

 the above list of proteids (a-g), with Millon's reagent. 

 Record results. 



(5) The Biuret test. 



To a suspected liquid add an excess of sodic hydrate; 

 shake well and to the mixture add one or two drops 

 of a very dilute solution of cupric sulphate. A violet 

 color appears which on heating becomes deeper in 

 shade. 



A most convenient reagent for this reaction is a 

 mixture of the solutions (a) and (b) of the Fehling's 

 test not in equal quantities as in the typical Fehling's 

 solution, but in the proportion of nine parts of the 

 sodic hydroxide solution (b) to one part of the cupric 

 sulphate solution (a) and add an equal volume of dis- 

 tilled water to the mixture. 



Tabulate results on the proteid series (a) to (g). 



(6) Subject each of the series of proteids (a) to (g) to 

 each of the following reagents tabulating results: 



(I) Picric acid, saturated solution. 



(II) Absolute alcohol. 



(III) Mercuric chloride, saturated solution. 



(IV) Tannic acid, saturated solution. 



(V) Silver nitrate, 10% solution. 



(VI) Ammonium sulphate, saturated solution. 



