FECES. 543 



to a sourish odour. The taste is sweetish bitter. The colour of 

 vegetable blue infusions is not altered by fresh feces, indicating 

 the absence of any uncombined acid or alkali.* 



1. The consistency of human feces varies considerably in dif- 

 ferent circumstances ; but at a medium, they may be stated to 

 lose three-fourths of their weight when dried upon a water-bath.f 



2. They do not mix readily with water ; but by sufficient agi- 

 tation and maceration, they may be diffused through it. The 

 liquid, in this state, being strained through a linen cloth, leaves 

 a matter of a grayish-brown colour, retaining a peculiar odour, 

 which adheres long and obstinately to all those substances that 

 come in contact with this residue. When dried, this substance 

 exhibits the remains of vegetable matters used in food, and per- 

 haps also of some animal matters. Its quantity amounts to about 

 seven per cent, of the feces.J 



3. The strained liquid deposited, on standing, a yellowish- 

 green slimy matter, which was separated by the filter. It amount- 

 ed when dry to fourteen per cent, of the feces employed. From 

 the numerous experiments of Berzelius upon this matter, it ap- 

 pears to be composed chiefly of three substances: 1. A fatty 

 matter, separated by means of alcohol, which possesses many 

 properties in common with picromel, and which Berzelius con- 

 siders as that substance a little altered. 2. A peculiar yellow- 

 coloured substance, dissolved by water after the fatty matter is 

 removed. This substance Berzelius compares to gelatin ; but it 

 appears to be rather more closely allied to mucus, or, at least, to 

 contain mucus as a constituent. It dissolves in water, but not in 

 alcohol ; tannin makes its solution muddy, but occasions no pre- 

 cipitate ; acetate of lead occasions a copious white precipitate, 

 but does not deprive the solution of its yellow colour. It soon 

 runs to putrefaction, exhaling the odour of putrid urine. 3. A 

 greenish-gray residue, insoluble both in water and alcohol, and 

 leaving, when incinerated, some silica and phosphate of potash. 



4. ,The liquid which passed through the filter was at first light- 

 yellow ; but by exposure to the air it became brown, which gra- 

 dually deepened in colour, till the solution grew at last muddy. 

 When concentrated by evaporation, small transparent crystals 

 made their appearance : which proved, on examination, to be 

 crystals of ammonia-phosphate of magnesia. The solution, on 



* Gehlen's Jour. vi. 512. f Ibid. vi. 535. J Ibid. vi. 513. Ibid. 526534. 



