82 
MR. STENeOUSE ON THE EXAMINATION OF THE 
Evernesic acid may be still more advantageously prepared by employing baryta 
water instead of potash. When evernic acid is boiled for a short time in a slight 
excess of baryta water, much carbonate of baryta falls. This is to be removed and 
the solution saturated with muriatic acid, when the evernesic acid precipitates in 
silky needles which have a slightly yellowish tint. By being redissolved and treated 
with animal charcoal, they are rendered colourless. The mother-liquor from which the 
evernesic acid has been precipitated, when evaporated to dryness, yields a consider- 
able quantity of orcin. Evernesic acid has neither taste nor smell. It is little soluble 
in cold, but very soluble in boiling water. It dissolves readily in hot spirits, and to 
some extent also in ether. Its aqueous and alcoholic solutions redden litmus paper. 
When heated in a test tube, it emits an agreeable smell and yields a white crystalline 
sublimate. Though orcin is always found in the mother-liquors from which the 
evernesic acid has been obtained, yet when evernesic acid itself is boiled a second 
time with either potash or baryta, no orcin is produced, showing that the orcin has 
been derived solely from the decomposition of evernic acid. Hypochlorite of lime 
merely gives a yellow colour with evernesic acid; and when it is dissolved in ammo- 
nia and exposed to the air, no red colour is produced. When evernesic acid was 
dried in vacuo and then at 212° F., it lost no water. 
I. O' 191 grm. substance gave with chromate of lead 0'415 Cog and 0*0995 water. 
II. 0*243 grm. substance gave 0*53 carbonic acid and 0*124 water. 
Calculated numbers. 
I. 
II. 
18 C 1375*830 
59*80 
59*25 
59*48 
10 H 124*795 
5*42 
5*78 
5*66 
8 O 800*000 
34*78 
34*97 
34*86 
2300*625 
100*00 
100*00 
100*00 
These analyses give Cjg HyOy-j-ITO for the rational formula of hydrated evernesic 
acid. 
Baryta Salt. 
The baryta salt of evernesic acid is easily formed as follows. A quantity of evernic 
acid is boiled for a short time with a slight excess of baryta, and the solution neu- 
tralized by a stream of carbonic acid gas. The filtered liquid which contains the 
baryta salt and some orcin is to be evaporated to dryness on the water-bath. The 
orcin and the colouring matter which accompany the salt may be removed by treat- 
ing the dry residue with either cold alcohol or ether, in both of which liquids the 
salt is nearly insoluble. If the salt is then digested in weak spirits, it readily dissolves, 
and is deposited on the cooling of the solution in large hard four-sided prisms ar- 
ranged in a fan-like shape. If not quite colourless at first, the crystals may be easily 
rendered so by repeated crystallizations. 
I. 0*228 grm. salt dried two days in vacuo, gave 0*083 BaO Co2=0*0643 BaO = 28*20 
per cent. BaO. 
II. 0*355 grm. salt gave 0*5331 carbonic acid and 0*137 water. 
