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SELECTED ARTICLES. 
position of this being C 28 H 10 4 , that of the hyduret will be 
C 28 H 12 4 . I have made four analyses by combustion with 
the oxide of copper on perfectly anhydrous products. To ob- 
tain the hyduret in this state, I first rectified it over fused 
chloride of calcine for twenty-four hours. The oil having 
been poured off, was distilled, and when one half had passed 
over, the remainder was obtained separate. It was from this 
latter that the following results were obtained: 
I. II. III. IV. 
Carbon, 69.45 69.11 " 69.44 
Hydrogen, 4.86 4.89 4.88 5.07 
Oxygen, 25.69 26.00 " 25.49 
100.00 100.00 " 100.00 
This, by calculation, would give: 
C 23 1070.15 69.26 
H 12 74.88 4.84 
0* 400.00 25.90 
1545.04 100.00 
According to this, the hyduret of salicyle is isomeric with 
hydrated benzoic acid. 
To ascertain whether, in the state of vapor, the two sub- 
stances would exhibit a difference in condensation,! ascertain- 
ed the density of the vapor by the process of M. Dumas. The 
results were as follows: 
Excess of weight of globe full of vapor over same 
full of air, 0^.421 
Volume of globe in cubic centimetres, 233 
Temperature of vapor marked by a mercurial thermometer, 
230° c. corresponding to 225 of an air thermometer: 
Temperature of the atmosphere, 13° 
Pressure, m .764 
Air remaining in the vapor, 0.0 
Density of the vapor, 4.276 
The density which M. M. Dumas and Mitscherlich each 
