PRODUCTS OF DECOMPOSITION OF COMENIC ACID. 231 
Hence the composition of the salt dried at 212° is expressed by the formula 
4 BaO HO C,, H, O,. 
In the crystals, as appears from the following experiments, two equivalents of 
i this substance are combined with thirteen of water. 
j 
{ 14-815 grains air-dry substance lost at 212° 
q 3105... water. 
2 10-721 grains air-dry substance lost at 212° 
2:°228 ... water. 
The per-centage calculation from which, 
if Il. Mean. 
20:95 20-78 20°86 









agrees well with the number, 20°73, required by the formula 
2 (BaO, HO, C,, H, O,)+13 aq. 
Neutral Comenate of Baryta.—An alkaline ammoniacal solution of comenic 
acid causes an immediate precipitate in chloride of barium, of minute radiated 
crystals. In dilute solutions these do not appear immediately, but in a very short 
time they commence forming, and their quantity increases till the whole fluid is 
filled. Under these circumstances they present a very beautiful appearance, being 
in individual groups, whose silky needles radiate regularly from a centre. Under 
the microscope these needles are seen to be square prismatic crystals. 
This salt is insoluble in boiling water, and does not lose its water of crystalli- 
zation at a temperature of 212°. When dried at 250°, it is almost pyrophoric on 
ignition, blowing up in a light fiery cloud; for this reason the base was deter- 
mined as sulphate in the analysis which follows, by ignition with a little sul- 
phuric acid. 



5-418 grains dried at 250° Fahr. gave 
4:584 ... carbonic acid, and 
0-721 ... water. 
5:556 grains dried at 250° Fahr. gave 
4194 ... sulphate of baryta. 
Experiment. Calculation. 
ee ne a ee 
Carbon, . ” 23:07 23-27 Ci. 72 
Hydrogen, , 1:47 1-29 H, 4 
Oxygen, . : oon 25°89 0,5 80 
Baryta,  . ° 49°54 49°55 2BaO 143-28 
100-00 100-00 309-28 
From the above it appears that this salt, like the corresponding one of lime, 
retains two equivalents of water at this temperature, its formula being 
2 BaO, C,, H, 0,+2 HO, 
