1819.] produced during the Calcination of Mucic Acid. 267 



crystallizations, unless we distil them in a small retort furnished 

 with a receiver at a temperature of about 266°. They begin to 

 melt, and then distil like chloride of antimony, leaving in the 

 retort merely a small black residue. The distilled acid retains a 

 slightly yellow colour ; but a single crystallization is sufficient to 

 render it perfectly pure : 150 grammes of mucic acid give about 

 60 grammes of the liquid, from which we obtain 8 or 10 grammes 

 of pure acid. 



This acid, which I shall distinguish hereafter by the name of 

 pyromucic, is white, destitute of smell, of a strong acid taste, 

 melts at the temperature of 266°, and is volatilized a little above 

 that temperature, condensing into a liquid, which is converted 

 on cooling into a crystalline mass, the surface of which is covered 

 with fine needles, and it leaves only traces of a residue. When 

 placed on red-hot coals, it melts, and is volatilized in white, 

 penetrating vapours. When exposed to the air, it does not 

 attract moisture. It strongly reddens litmus, is much more 

 soluble in boiling than in cold water. Hot water saturated with 

 it deposits it on cooling in small elongated plates, which cross 

 each other in all directions. Water, at the temperature of 59°, 

 dissolves -'^th of its weight of it. Alcohol dissolves it more 

 abundantly than water. 



This acid, subjected to analysis by means of peroxide of 

 copper, gives the following constituents : 



By weight. By volume. 



Carbon 52-118 371 



Oxygen 45-806 120 



Hydrogen 2-111 84 



If we reduce the volumes to more simple numbers, we obtain 



Carbon 9 



Oxygen 3 



Hydrogen 2 * 



This acid unites readily with the different metallic oxides, and 

 is neutralized by them. Most of its salts are soluble, and capable 

 of crystallizing. 



Pyromucate of potash is very soluble in water and alcohol, 

 and crystallizes with difficulty. When evaporated to a pellicle, 

 it assumes the form of a granular mass, which deliquesces in 

 the air. 



Pyromucate of soda likewise crystallizes with difficulty, 



• This is nearly, S atoms carbon = 6-75 



6 atoms oxygen = 6 - 00 



2 atoms hydrogen =■= - i!5 



1300 



*o that if the analysis in the text be correct, the weight of an atom of this acid 

 ii 13.— T. & 



