374 Mr. W. Brande's Observations on Albumen , 
passed the filter, as a solution of nearly pure mucus ; but 
found, on applying to it the tests of nitrate of silver, and ace- 
tate of lead, that it still contained a very considerable propor- 
tion of saline matter. The precipitate consisted of muriate 
and phosphate of silver and lead, in combination with a little 
animal matter, the odour of which was perceptible on expos- 
ing it to heat after it had been washed and dried. 
One thousand grains of saliva, afforded by careful evapora- 
tion in a water bath, a residuum weighing one hundred and 
eighty grains, from which twenty grains of saline matter, 
consisting of phosphate of lime and muriate of soda, were 
obtained by incineration. 
2. The mucus from the trachea, and that of the oyster were 
next examined ; but here the proportion of saline matter was 
greater than in the former case, although no traces of albu- 
men could be detected by the usual tests of heat, alcohol, and 
acids. 
Finding, therefore, that the re-agents employed, to detect 
mucus,* act principally upon the salts which it contains, and 
not merely upon the secretion itself, it became an object of 
some importance to find out a method of depriving it of its 
saline ingredients, by such means as should not affect the 
mucus. Decomposition by electricity immediately occurred to 
me, as the most likely means of attaining the object I had in 
view. 
For this purpose, I procured three glass cups, each capable 
of holding rather more than a measured half ounce of water; 
one of these was filled with a mixture of equal parts of saliva 
* Nitrate of silver and acetate of lead. Vide Thomson’s System of Chemistry, 
Vol. V. page 500. 3d edition ; and Nicholson’s Journal, XI— 251. 
