Dr. Pearson on expectorated Matter. 319 
alkalies in a proportion which leaves the liquor turbid ; nor 
for some time after the putrefactive process had appeared. 
But these globules disappear with such a proportion of sul- 
phuric acid as detaches charcoal ; or of nitric acid, and of liquid 
potash, as produce a clear solution : also by charring by fire. 
It is perhaps superfluous to remark, that these atomic glo- 
bules are quite different from the air bubbles usually entan- 
gled in this kind of matter, as perceived by the microscope ; 
the latter differ much from the former, in being of far greater 
magnitude — in being less numerous — in being transparent, 
and disappearing on agitation, or heating the matter, or even 
by mere standing. 
For the most part this expectorated substance swims on 
water ; but by agitation or stirring to disengage air bubbles, 
or by merely standing, it sinks. Some of the lumps suddenly 
hawked up, immediately fall to the bottom of a vessel of 
water. No signs of either acid, or alkali, appeared on the trials 
of this matter with well known reagents, provided it was free 
from extraneous matter ; but it was apt to betray acidity from 
things taken with the food or drink. 
4. Puriform matter. I have seen this matter expectorated in 
several diseases in the quantity of two or three ounces to half 
a pint in twenty-four hours, on some rare occasions, without 
any breach of surface. I believe it would be considered by 
every one to be pus , having the properties commonly admitted 
to be those of this substance. It will however, perhaps, only 
be just to call it puriform, for the present, as it appears to 
me probable, that I shall hereafter be able to show that it 
possesses properties not belonging to pus of abscesses, al- 
though in the obvious, or sensible properties, it is similar to 
Tts 
