and naphthaline, and on a new acid produced. 151 
leaving sulphate of baryta, differ probably only in the quan- 
tity of combustible matter present, or its mode of combina- 
tion in the acid. 
It is this circumstance, of the formation of a second salt in 
small but variable quantities with the first, which must be 
guarded against, as before mentioned, in the preparation of 
salts from the impure acid. It varies in quantity according 
to the proportions of materials, and the heat employed : and 
I have thought that, when the naphthaline has been in large 
quantity, and the temperature low r , the smallest quantity is 
produced. When the impure acid is used for the preparation 
of the salts now under description, a small portion of it 
should be examined by carbonate of baryta, as above, and 
rejected, if it furnish an important quantity of the flameless 
salt. 
These bodies may be distinguished from each other provi- 
sionally, as the flaming and the glowing salts of baryta, from 
their appearances when heated in the air. The latter is more 
distinctly crystalline than the former, and much less soluble, 
which enabled me by careful and repeated crystallizations, to 
obtain both in their pure states. 
The flaming salt (that corresponding to the acid now under 
description ) when obtained by the slow evaporation of the 
saturated solution, formed tufts, which were imperfectly 
crystalline. When drops were allowed to evaporate on a 
glass plate, the crystalline character was also perceived ; but 
when the salt was deposited rapidly from its hot saturated 
solution, it appeared in the form of a soft granular mass. 
When dry, it was white and soft, not changing in the atmo- 
sphere. It was readily soluble in water and alcohol, but was 
