16 i ]Mr. J. F. Bromi on some Sails and Products of 



in crystals of considerable size. 3"41 grains aqueous solution of 

 this salt at 60° gave 1-08 grain of residue at 212° = 0-31 per 

 cent. 



6-15 grains substance gave 10'26 carbonic acid and 1*56 water. 

 6-3J? grains substance gave 2"31 carbonate of lime. 



Calculation. 



Experiment. < -^ 



Carbon . . 42-94 42-85 C'o 60 

 Hydrogen . 2-60 2-85 H* 4 



Oxygen . . 34-02 34-30 0« 48 



Lime . . . 20-44 2000 CaO 28 



"^ 



100-00 100-00 140-00 



Hence the composition of the salt is represented by the for- 

 mula CaO, C^" H^ 0^ + HO. 



Pyrumeconate of Magnesia. — A warm aqueous solution of py- 

 romeconic acid gives ^^■ith acetate of magnesia a white amorphous 

 precipitate, insoluble in water and alcohol. In its properties it 

 closely resembles the other pyromeconates. The following is 

 the analysis of the salt, the magnesia being determined by igni- 

 tion of it, and weighing the residue. It loses nothing at 212°. 



4-925 grains substance gave 8-735 carbonic acid and 1-235 

 water, 4-595 trains substance i!;ave -76 majruesia. 



100-00 100-00 123-67 



From which it appears that this is the only earthy salt of py- 

 romeconic acid which is anhydrous, the composition of it being 

 expressed by the formula MgO, C^" H^ 0^ 



Pyroineconatc of Lead. — Yv'hcn a warm concentrated solution 

 of pyromeconic acid, made ammoniacal, is added to acetate of 

 lead, it causes an immediate precipitate of a dense crystalline 

 powder, which rajiidly increases upon violent agitation of the 

 fluid. This salt, as has already been mentioned, was prepared 

 and analysed by Robiquet, who formed it by adding hydratcd 

 oxide of lead to a hot solution of pyromeconic acid ; he found it 

 to be anhydrous, and to consist of PbO, C'** H^ 0^. 



The crystals require a considerable qttantity of hot water for 

 their solution ; they are not so soluble in alcohol either hot or 

 cold. It is colourless when thrown down, but rapidly becomes 

 yellow by exposure for any length of time to bright daylight. 



