584 Chemical Properties of Animal Fluids. [Nov, 



may be produced from mucus by alcohol, as from biliary matter 

 by ether. 



Bile itself is often of such a mucous consistcrce as to be 

 drawn out in threads. This is owing to the presence of mucus 

 dissolved in the alkali of the bile. A very little of any acid (the 

 acetous for example) precipitates the mucus, and destroys the 

 viscosity of the bile. Alcohol has the same effect. 



Former chemists seem to have regarded this property of bile 

 as owing to the presence of albumen, the existence of which 

 has been considered as demonstrated by the precipitate caused 

 by adding acetic acid or alcohol. From what I have already 

 mentioned, it is clear that no precipitate produced by acetic acid 

 can be albumen, since the latter is soluble in this acid ; and as 

 bile is not disturbed by prussiate of potass or by tannin after the 

 precipitate by acetous acid is removed, this is a proof that no 

 albumen can be contained in bile. The following experiment is 

 conclusive that the supposed albumen of bile is only mucus: mix 

 some bile with very weak sulphuric acid, drain on a filter the 

 yellow precipitate thus formed, and then digest it with a satu- 

 rating quantity of carbonate of soda and water, and the precipi- 

 tate will be changed to a mucus, which will be more or less 

 glairy, according to the quantity of water employed. 



The Mucus of' the Intestines accompanies the excrements, in 

 which it often forms long and transparent filaments. "When 

 once dried, the addition of water will not restore its mucous 

 property, but alkalies produce this effect, though without ren- 

 dering it transparent. 



The Mucus of the Urinary Passages accompanies the urhie, 

 in which it is partly dissolved, and partly suspended mechani- 

 cally. The latter portion is generally too transparent to be 

 distinguished by the eye ; but it may be exhibited by letting the 

 urine remain awhile at rest, decanting the fluid, portion, and 

 drying the mucus on a filter. This loses its' mucous property 

 totally by desiccation, and then often becomes rose-coloured, 

 owing to the presence of uric acid, and appears to be crystal- 

 lized. It softens a little in water. The urinary mucus is easily 

 soluble in alkalies, and is not separated from this solution by 

 acids. Tannin separates it in white flocculi. I shall return to 

 this subject under the analysis of urine. 



4. Fluids of the Serous Membranes. 



It is well known that the surface of serous membranes is 

 always moistened by a liquid, which in a state of health is never 

 secreted in quantities sufficient for analysis ; it is therefore only 

 during a dropsical state of these membranes that wc can gain 

 any knowledge of its properties. This fluid may be considered 

 as serum deprived of from $- to $ of its albumen. It does not 



