8 HANDBOOK FOE BIO-CHEMICAL LABOEATOEY. 



Soap. 



Preparation. Dissolve 50 grms. fatty acids (page 7) in 

 100 c.c. alcohol by warming on the water-bath. Gradually 

 add an alcoholic solution of caustic soda (10 grms. NaHO in 

 100 c.c. alcohol) to this solution until a very faint alkaline 

 reaction is obtained. Heat on water-bath for 15 minutes, 

 transfer to flat porcelain dish, and evaporate off the alcohol 

 on the water-bath. When nearly all alcohol is off, add 30 c.c. 

 water and continue the evaporation, stirring all the while. 

 The product thus obtained when drv will be a neutral soap. 



Serum Albumin. 



Preparation. 1. Defibrinated ox blood (or human transu- 

 dations) is filtered through washed linen (free from starch) 

 and allowed to stand in the cold in a tall vessel until the red 

 blood-corpuscles have settled to the bottom. The clear serum 

 is carefully drawn off by means of a siphon and saturated at 

 30 C. with magnesium sulphate, filtered at the same tem- 

 perature, and washed with a saturated solution of magnesium 

 sulphate. Saturate the filtrate with sodium sulphate (or 

 ammonium sulphate) at 40 C., whereby the serum albumin 

 is precipitated. This precipitate is collected on a filter, 

 pressed between paper, dissolved in water, reprecipitated by 

 sodium sulphate (or ammonium sulphate), and the process 

 repeated several times. The solution in water is now freed 

 from salts by means of dialysis, using large amounts of dis- 

 tilled water. The serum albumin may be obtained from this 

 dialyzed solution by evaporating the solution to dryness at a 

 gentle heat, or, better, by precipitating with an excess of 

 strong alcohol, filtering, washing with alcohol, and finally 

 with ether, and then drying by exposure to the air. 



When precipitating the serum albumin by means of alcohol 

 filter immediately, press between paper, and remove the alco- 

 hol from tte precipitate by means of ether. 



