reichert's distillation process. 39 



NOTES ON KEICHERT'S DISTILLA.TION PROCESS FOR 

 THE IDENTIFICATION OF BUTTER-FAT. 



An abstract of Reichert's original paper appears in the Chemical 

 Society's Journal, Vol. 36, 1879, p. 406. The facts (1) that butter- 

 fat is distinguished from other animal and vegetable fats likely to be 

 used in the sophistication of butter, by containing about 6 to 7 per 

 cent, of butyric acid (as butyrin), and (2) that this acid is sufficiently 

 volatile to make it possible to distil it over in a current of air, are 

 made the basis of this process, which was originally carried out by 

 Reichert as follows : — 



2.5 grammes of the dry, filtered fat were weighed in the liquid 

 state into a 150 c.c. flask, and saponified by the addition of 1 gram 

 solid potassic hydrate dissolved in 20 c.c. of 80 per cent, alcohol ; 50 

 c.c. water were then added, and then 20 c.c. dilute sulphuiic acid 

 (1 to 10 by volume). The mixture was then distilled, a slow stream 

 of air being aspirated through. After 15 c.c's distillate was collected, 

 this was returned to the distillation-flask, and the distillation con- 

 tinued till 50 c.c. was collected. This was titrated with deci-normal 

 soda, litmus being; the indicator. Reichert found that an average of 

 14 c.c. deci-normal soda was required to neutralize the acid in this 

 distillate, with a variation of ±; 0.45 c.c. 



Medicus and Scherer [Zeifschrift fiir Analyt. Chemie, 1880, p. 

 159,) have examined this method, and highly recommend it. Vari- 

 ous changes in it have been suggested, as by Meissl, who uses 5 

 grammes butter-fat, and a weaker alcohol for dissolving the alkali 

 requisite for saponification in order to avoid the loss of volatile acid 

 by etherization during saponification. Meissl collects 110 c.c. dis- 

 tillate, and finds a minimum of 26 c.c. deci-normal soda requisite 

 for neutralization. 



C. E. Schmitt uses phosphoric acid instead of sul^^huric for decom- 

 posing the soap. 



A. H. Allen Analyst, Vol. X., p. 103,) has examined the process, 

 and reports favourably upon it. He saponifies 2.5 grams fat with 

 25 c.c. semi-normal potash in a closed flask, and after evaporating 

 off" the alcohol on a steam bath, dissolves the soap in water, adds 

 excess of dilute sulphuric acid, and makes up to 75 c.c, distilling 

 over 50 c.c. He finds a minimum of 12.5 c.c's deci-normal alkali 

 required to neutralize this distillate. 



