On the Functions of the Bile as a Solvent. 



73 



have taken as the lowest practicable limit in making our determina- 

 tions. The solubility of the mixed calcium or magnesium soaps in bile 

 is difficult to accurately determine on account of the undissolved resi- 

 due of palmitate and stearate left behind. When even as little as 

 0*1 per cent, of either mixture is added to ox bile a residue is obtained. 

 The magnesium soaps are somewhat more soluble than the calcium 

 soaps, but in both cases the solubility is very low. In the case of the 

 mixed calcium soaps, apparently none is taken up into the solution 

 -after 0*2 per cent, has been added ; and in the case of the mixed 

 magnesium soaps the same result is attained after the addition of 

 about 0'4 per cent. Similar results are obtained in the case of the 

 mixscl soaps with bile-salt solution alone, and with bile-salt plus 

 lecithin. A bile-salt solution (5 per cent.) ceases to dissolve more 

 when 0*1 per cent, of mixed calcium soaps has been added or 02 per 

 cent, of mixed magnesium soaps ; and the figures are almost doubled 

 when 1 per cent, of lecithin is dissolved in addition in the bile-salt solu- 

 tion used. 



When the solubilities of the separated soaps in bile-salt, or in bile- 

 salt plus lecithin, solutions are tested, it is found that the solubilities 

 are only considerable in the case of the oleates ; and here again it is 

 seen that the magnesium salts are more soluble than the calcium salts. 



Calcium oleate, in bile-salt solution, 0'2 per cent. ; in bile-salt plus 

 lecithin solution, 1*4 per cent. 



Calcium palmitate, in bile-salt solution, less than 0*1 per cent. ; in 

 bile-salt plus lecithin solution, 0*9 per cent. 



Calcium stearate, in bile-salt solution, less than 0*1 per cent. ; in bile 

 ssalt plus lecithin solution, 0'4 per cent. 



Magnesium oleate, in bile-salt solution, 3*2 per cent.; in bile-salt plus 

 lecithin, 8*2 per cent. 



Magnesium palmitate, in bile-salt solution, 0'2 per cent. ■ in bile-salt 

 plus lecithin, 1 -2 per cent. 



Magnesium stearate, in bile-salt solution, less than 0'1 per cent. ; in 

 bile-salt plus lecithin solution, 1 "0 per cent. 



The physiological importance of the solubilities of the calcium and 

 magnesium soaps in bile has, in our opinion, been much overrated. 

 Although the figures above given show that the solubilities of the 

 mixed soaps of calcium or magnesium are very low, and hence that the 

 usual statement that these bodies are soluble must be modified, a point 

 of more physiological import is that the percentage of such soaps 

 formed in the intestine during digestion of fat must be very small 

 under normal condition, and hence their solution by the bile is of no 

 great physiological moment. Such solubilities as are quoted above, 

 low though they be, are in any case, more than sufficient to account for 

 the absorption of such minimal amounts of calcium or magnesium soaps 

 as may be formed during fat digestion. 



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