and Experiments on Pus . 315 
mass like pus, or into small curdy masses in a very large pro- 
portion of whey coloured liquid, like mucous sputum. Thick 
pus affords on evaporation to brittleness, -i or J residue ; and 
transparent sputum of the consistence of jelly, gives about - r _ 
or y- of such residue ; but this opaque matter under inquiry, 
affords — to T y of brittle residue, according to the proportion of 
the two substances. I could not separate the supposed pus and 
mucus from one another, to exhibit them distinctly by water, 
or by any other means, on account, as I conceive, of the inti- 
mate diffusion through one another, and their mutual cohesion. 
But on evaporating the milky water, produced by agitating 
this sputum in it, or by letting it stand to collect the sediment, 
little else beside a mere congeries of globules seen under 
the microscope, was thus obtained. For the same reason, 
on standing, a serous liquid like that of pus (Sect. VII. 1) 
does not separate, or only partially, from the opaque part, so 
as to render it possible by ablution, to collect this coagulable 
liquid like that of pus : and the greater proportion of water, 
belonging to the mucus, occasions the coagulation by caloric, 
to afford only a milky liquid, instead of an uniform mass of curd. 
This kind of sputum, consistently with the phenomena, 
must be produced by secretion from the bronchial membrane 
in its entire state, and not by ulceration or abscess. For it is 
secreted in many cases, at the rate of a pint or more in each 
24 hours, for we.ks and months successively, and for 20 or 
more successive winters. Also many persons recover their 
good health after this secretion, and it is the usual termination 
favourably of pneumonia, bronchitis, &c. It is produced by 
any disease of great irritation of the lungs ; as I have found 
