PRODUCTS OF DECOMPOSITION OF COMENIC ACID. 243 
A solution of the crystalline ammonia salt gives, with nitrate of silver, a white 
gelatinous precipitate, which partially decomposes in boiling water. The same 
solution made alkaline gives, with nitrate of silver, a yellow flocky precipitate, 
which almost instantly passes through deepening shades of colour into a heavy, 
black, amorphous precipitate. The same solutions give, with acetate of lead, 
heavy insoluble precipitates; the acid solution gives, with sulphate of copper, a 
grey precipitate. 
I have examined more fully and analyzed two or three of the salts of come- 
namic acid. 
Comenamate of Ammonia.—Comenamic acid dissolves readily in ammonia, 
when the alkali is added in excess, and such a fluid deposits no salt on standing ; 
but if ammonia be added to a boiling aqueous solution of the acid, in such quan- 
tity that the reaction remains slightly acid, the ammonia salt crystallizes out on 
cooling of the fluid in small grains, which, when magnified, are found to consist 
of bundles of needles radiating from a centre. They are difficult of solution in 
boiling water, but do not always reappear quickly when the liquid is cold. Their 
solution shews the phenomenon of epipolic dispersion very beautifully, when ren- 
dered alkaline by ammonia. They are anhydrous. 


‘ 5°623 grains dried at 212° gave 
8-570 ... carbonic acid, and 
2:446 ... water. 
4-945 grains dried at 212° gave 
12-715 ... platinum salt of ammonia, 
Experiment. Calculation, 
——————_———_ 
Carbon, , . 41:56 41°86 Ca 72 
Hydrogen, 5 4:83 4:64 H, 8 
Oxygen, : ain 37°23 0, 64 
Nitrogen, . 16:14 16-27 N, 28 
100-00 100-00 100 
The above analysis leads to the formula 
NH, 0, NH, C,, H, 0,. 
Comenamate of Baryta.—The salt I analyzed was obtained by adding a solu- 
tion of the ammonia salt to chloride of barium; a precipitate was obtained in 
radiated groups, which, on crystallization from boiling water, assumed the form 
of separate prisms. It had an acid reaction. 

5-055 ... carbonic acid, and 
1105 ... water. 
4-425 grains dried at 212° gave, when ignited with SO,, 
2:190 ... sulphate of baryta. 
{tvs grains dried at 212° gave 
