268 M. Labillqrdiere on a new Acid. [Oct. 



attracts moisture, aud is less soluble in alcohol than the salt of 

 potash. 



Pyromucates of barytes, strontian, and lime, possess nearly 

 the same properties. They are rather more soluble in hot than 

 cold water, crystallize easily in small crystals, not altered by 

 exposure to the air, and insoluble in alcohol. Pyromucate of 

 baiytes is composed of 



Acid 67-7 



Barytes 42-2 



Hence it results that, according to the analysis of the acid, 

 the ratio of the oxygen of the baiytes to that of the acid is 

 :: 4-43 : 26-34, or :: 1 : 6, and to the acid itself:: 1 : 13. 



Pyromucic acid neutralized by ammonia loses a portion of its 

 base by evaporation, and forms an acid salt, which crystallizes 

 with facility. 



The solution of this acid, when heated with an excess of oxide 

 of copper, is neutralized, and forms a salt, which, by evapora- 

 tion, is deposited in small greenish-blue crystals, less soluble 

 than pyromucates of barytes and strontian. 



Zinc dissolves in hot pyromucic acid, and with the evolution of 

 hydrogen. A salt is formed, which cements into a mass when 

 evaporated. 



Iron acts in the same way, and its protoxide forms a soluble 

 salt, precipitated greenish-white by alkalies. Peroxide of iron 

 forms an insoluble salt, of a yellow colour, similar to that of sub- 

 sulphate of mercury. It is obtained by precipitation. 



One of the most remarkable combinations of this acid is that 

 which it forms with oxide of lead, when heated with moist 

 carbonate of lead. It dissolves, and forms a neutral salt. The 

 liquid separated from the excess of carbonate holds the pyro- 

 mucate of lead in solution. When evaporated, brownish 

 globules collect on the surface, of an oily and transparent aspect, 

 which, being separated from the liquid, acquire on cooling the 

 softness and tenacity of pitch, and at last become solid, opaque, 

 and whitish. When the evaporation is continued, new globules 

 are formed, and the whole liquid is converted into this species of 

 salt, from which the acid and oxide of lead may be extracted 

 unaltered. 



Succinate of lead possesses similar properties with regard to 

 solubility. 



Oxide of silver dissolves likewise in pyromucic acid. By 

 evaporation, the liquid acquires a brown colour, and the salt 

 crystallizes in small white plates. 



The alkaline pyromucates form few precipitates with the 

 neutral metallic solutions, unless they be very concentrated ; and 

 when precipitates appear, they dissolve in a slight excess of acid, 

 or even of water. 



