

307 



the tats contained in the food into fatty acids, fats acquiring thereby 

 the property of being acted upon chemically by the bile, and of being 

 transformed into an emulsion. 



The chemical action, or saponification, induced by the fatty acids 

 under the above circumstances, was proved by the mixture acquiring 

 a strong acid reaction ; and it was further observed that the acid fil- 

 trate from the cold emulsion was not precipitated by hydrochloric 

 acid, showing apparently that fatty acids exert on bile a chemical 

 decomposition at least as extensive as hydrochloric acid. With the 

 view of determining precisely the amount of soap formed, a method 

 of analysis was adopted calculated to indicate the proportion of fatty 

 acid remaining unacted upon by the bile : the difference between the 

 fatty acids used and the result of the above operation was equal to 

 the weight of the fatty acids saponified. It was found, in three ana- 

 lyses, that the mixture of bile and fatty acids being exposed for three 

 hours (in Analysis II. for 3^ hours) to the heat of an open water-bath, 

 contained an amount of soap in which the proportion of fatty acids 

 was 30'21 per cent., 20'5 per cent., 11 '5 per cent, of that employed 

 in the analysis. The filtrate from the emulsion in analysis No. II., 

 mixed with the solution obtained by washing the emulsion with di- 

 stilled water, was treated for three hours on the water- bath with a 

 fresh quantity of fatty acids, which operation yielded a proportion of 

 fatty acid saponified equal to 12*7 per cent, of that used in the ana- 

 lysis. Finally, the filtrate and washings obtained in this last group 

 were mixed with another quantity of fatty acids, and exposed for three 

 hours to the heat of the water-bath, in which case the proportion of 

 fatty acid saponified was equal to 3*8 per cent, of that used in the 

 analysis. The various operations had been attended with the forma- 

 tion of an emulsion. 



In order to be certain that, after exposing a mixture of bile and 

 fatty acids to the heat of a water-bath for three hours, the chemical 

 action thus induced was completely exhausted, two analyses were 

 undertaken according to the process just mentioned, and with bile 

 from the same gall-bladder ; but in one operation the mixture was 

 heated for three hours, and in the other for six hours : the propor- 

 tion of fatty acid saponified was the same in both cases, showing that 

 after three hours the bile had ceased to act on the fatty acids. 



Having obtained the above results, an inquiry was next undertaken 



