Dr. Pearson on expectorated Matter. 337 
sure of the sediments of the last mixture (1), being distilled 
to about one eighth, the remainder was evaporated to the con- 
sistence of a thick extract. The distilled liquid did not appear 
to have received any impregnation, except what had altered 
a little the odour. This extract-like residue amounted to one 
forty-fifth to one eightieth the weight of the expectorated 
matter, according to the kind of this substance. It varied also 
according to the proportion of the matter to the acid men- 
struum. 
(6). The residue (2 , a) just mentioned, after digestion a 
second time, in the same quantity of acid, afforded a smaller 
quantity of extract-like matter than before. 
(r). The third digestion afforded still less of this sub- 
stance. 
( d ) . The fourth and fifth digestion gave somewhat less 
than the immediately preceding one. 
( e ) . The sixth digestion yielded nearly the same propor- 
tion of extract-like matter as the fourth and fifth. 
3. The undissolved matter, after these repeated digestions 
in vinegar (1, 2), being exposed to fire in a platina crucible, 
first flamed and partially melted ; then became apparently 
charcoal, which burned away to the state of a brown earth- 
like substance scarcely T ±- of the weight of the substance 
subjected to fire, and not above T of the expectorated 
matter by which it was afforded. It consisted chiefly of phos- 
phate of lime, with indications of carbonate of lime, of a sul- 
phate, of a muriate, of silica, or at least vitrified matter, and 
of oxide of iron. 
4. The extract-like matter, from the first digestion of the 
expectorated matter (2 a), by exposure to the air, in a few 
