66 



Messrs. B. Moore arid W. H. Parker. 



tents. But the process of preparing the sodium soaps easily demon- 

 strates that the mixed sodium soaps prepared either from beef or mutton 

 suet are only very sparingly soluble in water. When the mixture obtained 

 by boiling the fat is thrown into cold water, practically none dissolves, 

 and the excess of alkali can easily be washed off in this way. An 

 increase in the amount of oleate present raises the solubility in water, 

 so that a mixture of soaps obtained from pig's fat cannot be separated 

 in this way. When the mixed soaps derived from beef or mutton fat 

 are boiled with water, they do dissolve to a greater extent ; but the 

 solution sets, on cooling, to a stiff jelly, even when it contains as little 

 as 2 per cent, of the mixed soaps. 



It occurred to us, therefore, that it would be desirable to make com- 

 parative quantitative experiments as to the solubilities at body tem- 

 perature of such soaps in water and in bile respectively, in order to 

 determine whether bile possessed any function as a solvent in soap 

 absorption from the intestine. Opportunity was also taken to prepare 

 and test the solubility quantitatively of the so-called " insoluble soaps " 

 of calcium and magnesium, as well as of the separated and purified 

 oleates, palmitates, and stearates of sodium, calcium, and magnesium. 



Attention has previously been given to the solubility of the magne- 

 sium and calcium soaps, so far as we are aware, only in a qualitative 

 fashion ; and the unqualified statement has in consequence been made 

 by Neumeister* that these soaps are dissolved in the intestine by the 

 agency of the bile. 



There is, in addition to the solvent action of bile upon the various 

 fatty derivatives in the intestine, another point of view from which we 

 may regard the bile as a solvent, and ascribe to it a very important 

 function connected with the excretion into the intestine from the liver 

 of substances insoluble in water. It is well known that the bile con- 

 tains cholestearin and lecithin, and although these bodies are not present 

 in large percentage, they occur in greater quantity in the bile than in 

 any other fluid in the body, and further this is the only channel by 

 which these important degradation-products of metabolism are removed 

 from the body. 



Although the presence of these substances in the bile has long been 

 known, no one, so far as we are aware, has drawn any inferences as to 

 why they are excreted by the bile rather than any other excretory 

 channel, nor recognised the importance of the change in the physical 

 properties of the bile, whereby it is adapted for carrying off these 

 waste products to the intestine, and so acquires a specific function 

 possessed by no other fluid in the body. 



Both lecithin and cholestearin are insoluble in water, and hence 

 cannot be thrown out of the body in simple aqueous solution. This 

 fundamental fact suggests inquiries as to how these substances are 

 * ' Lehrbuch der physiologischen Cheinie,' Jena, 1897, p. 221. 



