130 Dr. Stenhonse on the 



at 212° F., they lost no weight. They were subjected to ana- 

 lysis in the usual way. 



I. 0-5203 gramme of this salt gave 0-7933 of carbonic acid 

 and 0-1011 grm. of water. 



II. 0*3684 gramme gave 0*5633 of carbonic acid and 0*0755 

 of water. 



Per cent. 

 I. 0-7292grm.of thesaltgave 0*2002 oxideofcopper = 27*45. 



0-0917 =2743. 



0-0277 =27*34. 



Calculated numbers. Percent. 

 Carbon 10= 764*350= 42*522 

 Hydrogen 3= 37*438= 2*099 

 Oxygen 5= 500*000= 27*822 

 CuO = 495*7 = 27-577 



100*00 100*00 1797-488 = 100*000 



This gives the formula C 10 H 3 5 4- CuO for the constitu- 

 tion of the salt, and the number 1301- 78 for the atomic weight 

 of the acid, the calculated number being 1302. 



Pyromeconate of Iron. 



When pyromeconic acid is boiled with hyd rated peroxide 

 of iron, it combines with the oxide, and forms a brownish-red 

 powder, which, when neutral, is very little soluble either in 

 hot or cold water. When a few drops of an acid are added; 

 however, it dissolves with a fine deep red colour, and is de- 

 posited on cooling in small cinnabar-red crystals. The best 

 way of obtaining this salt in crystals of considerable size and 

 beauty, is by adding persulphate of iron to a tolerably dilute 

 boiling solution of pyromeconic acid, and allowing it to cool 

 very slowly. 



The crystals after some hours are deposited in very distinct 

 rhomboids, having a blood-red colour, and a lustre very much 

 resembling garnets. Though not large their crystalline form 

 is easily discernible by the naked eye. The crystals are hard 

 and brittle, and their powder is of a cinnabar-red colour. 

 They are very difficultly soluble either in hot or cold water ; 

 and their solutions are of a reddish yellow colour. 



When dried at 2I2°F. they were subjected to an analysis 

 in the usual way. 



I. Determination of the iron: 0'5527 grm. of the salt gave 

 0-112 of oxide of iron =19*80 percent. 



II. 0*9135 grm. of the salt gave 0*184 of oxide of iron 

 = 20*14 per cent. 



III. 0*426 grm. of the salt gave 0*086 grm. of oxide of iron 

 = 20*19 per cent. 



