S g 6 Dr. Pearson's Observations and Experiments 
6. Nitrate of mercury (solution of mercury in nitrous acid) 
produced a whitish turbid liquid. 
7. Oxalic acid produced immediately a precipitation of white 
acicular crystals. 
8 . Tartrite of pot- ash (soluble tartar) being added, a preci- 
pitation took place which much resembled that which takes 
place on adding tartareous acid to tartrite of pot-ash ; but the 
precipitated matter by the liquid from the white lac did not 
re-dissolve on adding pot-ash. 
With respect to the nature of the liquid contained m white 
lac, it perhaps belongs to the genus of acids, because it changes 
turnsole to a red coloured substance, and neutralizes fixed alkali 
* and lime (g) (k). 
This acid liquid is most probably secreted at the same time 
with the white lac ; and therefore the white lac coccus, like the 
ant, and some other insects, has organs for secreting an acid. 
As this acid is destructible by fire (/) (g) (0> and as 11 af ' 
fords carbon (f), it must be referred to the animal or vege- 
table acids. 
From the precipitation of tartrite of pot-ash {m, 8) resem- 
bling tartar, this acid might be supposed to be the tartareous; 
but as this precipitate is not again dissolved on adding pot- 
ash; as it has no sour taste (c) ; as it evaporates in aoo of 
caloric {b) ; as the combination with lime is readily soluble 
in water, and decomposed by pot-ash (g) (m, 1) ; and as the 
combination with soda is a deliquescent salt (*), this acid 
cannot be considered to be the tartareous. Nor does this liquid 
appear, from the above experiments, to be any one of the 
other known vegetable or animal acids. The other proper- 
