66 PHILOSOPHY OF ZOOLOGY. 



gradually subsides, and it may then be collected on the 

 filter and washed. In this state it is white, and would 

 seem to contain phosphate of lime mixed with it. The 

 mucus is quite insoluble in water * ; it becomes transpa- 

 rent and horny in the acetic, sulphuric and muriatic acids, 

 but does not dissolve in them, and the alkalies separate 

 nothing from them. The mucus, therefore, contains no 

 earthy phosphate, though its appearance would lead to 

 suspect this earthy salt. It dissolves in caustic alkali, and 

 is again separated from it by the acids. A small propor- 

 tion escapes the action of the alkali, but yields to muriatic 

 acid, and is not separable from this acid, by an excess of 

 alkali. The mucus of the saliva is very easily incinera- 

 ted ; and though no phosphate 'of lime is detected in it 

 by the acids in its natural state, a considerable portion of 

 phosphate appears in the ash after combustion. 1 " 



The mucus of the nose presents the folio wing properties: 

 " Immersed in water, it imbibes so much moisture as to 

 become transparent, excepting a few particles that remain 

 opaque ; it may then be separated by the filter from the rest 

 of the water, and may be further dried on blotting paper, 

 till it has again lost nearly the whole of the moisture it had 

 imbibed. Mucus thus dried will again absorb water when 

 immersed in it, and resume its transparency ;' and this alter- 

 nate wetting and drying may be repeated an indefinite 

 number of times, but it thus gradually becomes yellowish 

 and more resembling pus. Five parts of recent mucus 

 absorbed by .95 parts of water, produce a glairy mass 

 which will not pour from a vessel. When mucus is boiled 

 with water, it does not become horny, nor does it coagu- 

 late ; the violent motion of ebullition rends it in pieces, but 



* This was considered by Dr BOSTOCK as albumen, and his mucus ap- 

 pears to be the Peculiar Matter of the saliva of BERZELIUS. 



