Page:Proceedings of the Royal Society of London Vol 60.djvu/470

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In 1858 Dr. W. Marcel* announced to this Society the discovery that bile possesses the remarkable property of dissolving to a clear solution large amounts of fatty acids, and mixtures of these, when heated above their melting points, and that, on cooling, these bodies are again thrown out as a fine precipitate or emulsion.

We have repeated these experiments, and are able to confirm the accuracy of Marcet’s observation. Thus we found that 6 c.c. of dog’s bile at 62° C. dissolved completely 1*5 grams of the mixed fatty acidsf of beef suet, and similar solubilities were found in other cases.

No other observations than these have, so far as we are aware, been made on the effect of temperature on the solubility of fatty acids in bile; although different writers have mentioned that fatty acids are soluble in bile, no measurements have been made of the extent of their solubility. AltmannJ has recently surmised that fats are absorbed from the intestine as fatty acids, dissolved in the intestine by the agency of the bile, but has made no quantitative experiments on the solubilities of the fatty acids in bile. The forgotten experiments of Marcet, mentioned above, led us to think that the fatty acids might possess, at the temperature of the, a fair amount of solubility in bile, and as the solubility at this temperature is that of most physiological interest, we have made a series of determinations of the solubilities of oleic, palmitic, and stearic acids, and of natural mixtures of these in the proportions in which they occur in lard, beef suet, and mutton suet, in the bile of the ox, pig, and dog.

Different methods were used in the determination of these solubilities :—

1. To a measured amount of the bile under experiment, kept at a temperature of 39° C., small weighed quantities of the fatty acid cinder experiment were added, until no more dissolved.

2. A quantity of bile was saturated at 39° C., with excess of the fatty acid, and filtered from the excess of undissolved acid through a

f Throughout this communication the expression “ fatty acids ” means the fatty acids present in fats, oleic, palmitic, and stearic acids. % ‘ Arch. f. Anat. u. Physiol.,’ 1889, Anat.-Abth., Suppl. Band, p. 86.
 * ‘ Roy. Soc. Proc.,’ 1858, vol. 9, p. 306.