REICHERT-WOLLXY PROCESS. 



317 



phenolphthalein for this purpose soon became apparent to many. 



N 

 To the number of cubic centimetres of r-r alkali used one-tenth 



is added. 



Beichert-WoUny Process. — Wollny, in a now classic memoir, 



studied the errors of the Eeichert-Meissl process ; these are : — 



(1) Error due to the absorption of carbonic acid during the 

 saponification (may amount to + 10 per cent.). 



(2) Error due to the formation of esters during saponification 

 (may amount to — 8 per cent.). 



(3) Error due to the formation of esters during the distillation 

 (may amount to — 5 per cent.). 



Fig. 42. — Reichert-Wollny Apparatus. 



(4) Error due to the cohesion of the fatty acids during distil- 

 lation (may in extreme cases amount to — 30 per cent.). 



(5) Error due to the shape and size of the distilling vessel 

 and to the time of distillation (may vary the results ± 5 per 

 cent.). 



To avoid these errors he lays down the following method of 

 working : — 



Five grammes of butter-fat are weighed into a round flask of 

 about 300 c.c. capacity, with a neck 2 cm. wide and 7 to 8 cm. 

 long ; 2 c.c. of a 50 per cent, soda solution and 10 c.c. of 96 per 

 cent, alcohol are added, and the fla.sk heated for half an hour on 

 the water-bath under a slanting inverted condenser ; between 

 the centre and the flask is a T piece, which )s closed, the limb 

 being turned upwards. At the expiration of half an hour the 



