and naphthaline y 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% 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 crystaUine 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 



