

242 MR HENRY HOW ON CERTAIN SALTS AND 
Calculation. 
SS 
L. Il. 
Carbon, . ‘ 46:00 46:32 46°45 Ci 72 
Hydrogen, ; 3°37 3°41 3-22 H, 5 
Oxygen, . : aoe Ao0 41:30 0, 64 
Nitrogen, : 9:17 Aor 9-03 N 14 
100-00 100-00 155 
It is obvious that this substance is an acid amide, analogous to oxamic acid, 
and that its constitution is expressed by the formula of acid comenate of ammonia 
minus two atoms of water = HO,NH,C,, H, 0,.* 
Tt crystallizes with four equivalents of water. | 
{ 10-250 grains air-dry acid lost at 212° 
1:955 ... water. 
7-810 grains air-dry acid lost at 212° | 
1:450 ... water. 
I. II. Mean. 
Per-centage, 19-07 18:56 18°81 
The number 18°84 is that corresponding to the formula 
HO, NH, C,, H, 0, +4 HO. 
Comenic acid, as obtained above, is in brilliant scales, very slightly soluble 
in cold water; the crystals effloresce, and partially lose their lustre in a dry 
atmosphere. It is soluble in boiling spirit, but very slightly in absolute alcohol. 
It has a powerful acid reaction; dissolves readily in excess of alkalies ; also with 
* extreme facility in the strong mineral acids. From a solution in any of these, 
ammonia, added in quantity not quite sufficient to neutralize the whole of the 
solvent, throws down a granular precipitate of the ammonia salt. Its aqueous 
solution imparts to salts of peroxide of iron a magnificent and deep pure purple 
colour, which is destroyed by a few drops of a mineral acid, but reappears on 
dilution of the fiuid with water. It is decomposed by boiling with caustic potass, 
with evolution of ammonia and production of comenic acid. 
It forms readily crystallizable salts with a certain proportion of ammonia, 
potass, and soda; these have an acid reaction. The acid remains completely in 
solution in a small quantity of water, when supersaturated with any alkali; if 
ammonia be employed, and the fluid be evaporated to dryness at 212°, the salt 
with acid reaction remains. 
It dissolves the earthy carbonates with effervescence, when heated with them 
in water; if the acid be in excess, a crystalline salt, with an acid reaction, is 
obtained ; if the carbonate predominate in quantity, almost the whole acid remains 
undissolved as some basic compound. 
* T have also obtained this substance from meconate of ammonia; the details of my experi- 
ments will be given in a future paper on the subject of some derivatives of meconic acid. 

