72 



Messrs. B. Moore and W. H. Parker. 



soaps by bile from such a naturally occurring mixture, and do not 

 mean that a mixture of soaps of unaltered composition is taken up to 

 the extent indicated. 



Of much more importance physiologically than the increase in 

 amount of soap taken up, due to the presence of the bile salts, is the 

 obvious physical change in character of the solution. After nitration 

 in each case from the excess of undissolved soap, a difference is observ- 

 able even at body temperature between the two solutions. The solu- 

 tion of slightly over 2 per cent, of soaps in distilled water is opalescent 

 like a starch or dilute glycogen solution, while that of over 3 per cent, 

 of the same soaps in bile is limpid and clear. On allowing the two 

 solutions to cool to the temperature of the room, the plrysical differ- 

 ences become much more marked, for the more dilute distilled water 

 solution sets into a stiff jelly so that the containing flask can be turned 

 upside down without causing any alteration in the shape of the jelly, 

 while the solution in bile remains quite limpid, and only a small part 

 of the dissolved soaps passes out of solution as a finely granular precipi- 

 tate. The formation of a jelly on cooling, in the case of the distilled 

 water solution only, is not due to the fact that a. larger quantity of 

 soaps passes out of solution here on cooling ; for no matter at what 

 temperature higher than that of the body bile be saturated with the 

 mixture of soaps, and hence no matter how much soap passes out of 

 solution on cooling, it never forms a jelly, but always a precipitate and 

 a clear supernatant fluid. 



Now the formation of a viscid solution and ultimately of a jelly is 

 one of the general properties of colloidal solutions, and hence the 

 above-described experimental difference in behaviour probably indi- 

 cates that soaps in solution in distilled water are in a more colloidal 

 condition, and accordingly in a less diffusible and absorbable condition, 

 than when dissolved in the presence of bile-salts. 



Sodium oleate has the following solubilities — in distilled water, 5'0 per 

 cent.; in bile-salt solution, 7 - 6 per cent. ; in bile-salt phis lecithin solu- 

 tion, 11-6 per cent. 



Sodium palmitate, in distilled water, 02 per cent. ; in bile-salt solu- 

 tion, l'O per cent. ; in bile-salt plus lecithin solution, 2*4 per cent. 



Sodium stearate, in distilled water, 0*1 per cent. ; in bile-salt solution, 

 0*2 per cent. ; in bile-salt plus lecithin, 0*7 per cent. 



3. Calcium and Magnesium Soaps. — The usual statement that 

 the " insoluble soaps " of calcium and magnesium are soluble in bile 

 receives considerable modification when tested quantitatively, for the 

 experiment shows that these soaps are only very sparingly soluble in 

 bile. Neither the mixed calcium or magnesium soaps derived from 

 beef suet nor their constituent salts, viz., the respective oleates, palmi- 

 tates, or stearates, are at all soluble in distilled water, that is to say, 

 the solubilhVy- in each case lies much below 0"1 per cent., which we 



