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subjecting it to the same process of extraction as faeces. Neither 

 could it be found in ox-bile, the urine, or the substance of the spleen. 

 From the difficulty of obtaining the contents of the human small in- 

 testine in a healthy state, its presence or absence in that part of the 

 alimentary canal has not yet been satisfactorily determined. 



The lime precipitate, after having been thus thoroughly deprived 

 of the excretine by ether, is next treated with hydrochloric acid, 

 and water or alcohol, by which means margaric acid is extracted 

 from it. The author is uncertain whether the margaric acid of the 

 faeces is free or combined with excretine, but he is disposed to con- 

 clude that the neutral fats are decomposed in the intestinal canal 

 and their acid set free. Not having been able to detect stearic acid 

 in human evacuations, he supposes that what is contained in the fat 

 of mutton or beef taken as food must be converted into margaric 

 acid in its passage through the alimentary canal. 



The lime precipitate, freed from excretine and dissolved in alcohol 

 by means of hydrochloric acid, forms a dark port- wine-coloured solu- 

 tion, from which the margaric acid is deposited. On then adding 

 water to the solution and concentrating it on the water-bath, a flaky 

 colouring matter separates, which, being purified by solution in ether 

 and washing with water, is obtained as a dark-brown or black amor- 

 phous substance, similar to the colouring matter of blood, and to 

 that which Dr. Harley has lately extracted from urine. 



The matters brought down with the lime having been thus ex- 

 tracted, the sediment which spontaneously subsides from the alco- 

 holic solution of faeces before its treatment with the milk of lime, is 

 next examined. This deposit appears to be complex in its nature ; it 

 has a strongly acid reaction, and presents under the microscope small 

 oily globules, mixed sometimes with crystals of excretine and accom- 

 panied by a yellow amorphous matter. By boiling with alcohol and 

 filtration, a residue remains which the author has not yet examined, 

 and two substances are obtained from the filtrate. The first is de- 

 posited on cooling ; when collected and dried on filtering-paper it 

 has a granular character and is quite colourless ; it is very sparingly 

 soluble in ether, fuses by heat, and burns with a bright fuliginous 

 flame, leaving a white residue consisting of phosphate of potash. 

 The author has not yet been able satisfactorily to decide whether 

 this is a pure immediate principle or not ; he is inclined to consider 



