42 THE PROTEINS. 



filtered, if necessary, and evaporated at 40 to a small volume. 

 The solution should be precipitated by alcohol and immediately 

 filtered. Press out the excess of alcohol as much as possible, and 

 wash out the remainder with ether. 1 Allow the ether to escape by 

 stirring the albumin in a mortar. 



86. THE PREPARATION OF A CRYSTALLIZED VEGE- 

 TABLE PROTEIN. The edestin of the hemp seed will serve 

 as an example. Digest about 10 grammes of ground hemp 

 seed for half an hour at 50 to 60 with about 50 cubic 

 centimeters of 10 per cent, sodium chlorid solution; then 

 filter. Divide the nitrate into two parts. Dilute one part 

 with warm water until it begins to be turbid. Let it cool 

 very slowly to nearly the freezing point. Put the second 

 part in a dialyzer and allow the salt to diffuse into the 

 surrounding water. In both cases microscopic crystals 

 will be found,, octahedral or tetrahedral in form. The 

 more slowly they are formed the more perfect they will be. 



87. Show that the crystals are insoluble in water, 

 but soluble in salt solutions. This solution precipitates 

 on dilution with water and coagulates by heating. It also 

 gives the Millon's and the xanthoproteid reactions. The 

 edestin is therefore a globulin. 



88. THE PREPARATION OF CRYSTALLIZED EGG ALBUMIN. 

 To 100 cubic centimeters of egg-white from fresh eggs add an 

 equal volume of a saturated solution of ammonium sulphate. 

 Beat the mixture thoroughly with an egg-beater or a fork to break 

 up the membranes and let it stand in a cool place for several 

 hours, then filter through muslin or paper until the filtrate is clear. 

 Add to the filtrate more saturated ammonium sulphate until a 

 permanent precipitate forms, after which drop in distilled water 

 until this dissolves, avoiding an excess. Now add acetic acid, 



1 This must be done away from the vicinity of any light or 

 fire. 



