Researches respecting the radical of Benzoic Acid. 275 
Lastly under certain circumstances, (of which we yet know but 
little, but it is probable chiefly when the chlorobenzéy! was not per- 
fectly free from chlorine), by saturation with ammonia an oily body 
may be observed, possessing an aromatic odor resembling bitter al-., 
monds, and by which the contained benzamide has the property, be- 
fore it is dissolved, to melt to an oil by warming with water, and again 
to separate from the solution in the form of drops of oil, which con- 
geal in a short time. 
Pure benzamide shews a remarkable phenomenon in its erystalli- 
zation. It deposites from a boiling hot solution by rapid cooling, 
pearly, leafy crystals very similar to chlorate of potassa. By long 
cooling and at a certain concentration, the whole liquid congeals to 
a white mass consisting of very fine, silky crystals resembling caffein. 
After one or more days and often after a few hours, large cavities 
may be observed in this mass, in the centre of which may be obsery- 
ed one single or several large well formed crystals, into which the 
silky fibre has been converted; and gradually this change of form 
spreads throughout the mass. 
The form of the crystals of benzamide is a right-rhombic prism, 
which by the enlarging of two opposite planes becomes tabular. They 
have a highly nacreous lustre, are transparent and exhibit upon water 
a fattiness, easily swimming on its surface. 
At 115° C. it melts to a water-like liquid, which congeals by cool- 
ing to a large-leaved crystalline mass, wherein are frequently found 
cavities with well formed crystals. Ata stronger heat it boils and 
distills over unchanged. Its vapor is similar in odor to bitter almond 
oil. It is easily inflammable and burns with a sooty flame. 
In cold water, the crystallized benzamide is so little soluble that the 
solution scarcely possesses taste. In alcohol on the contrary it is 
readily soluble. In boiling ether it is also dissolved, and from this 
solution in particular can be obtained in well defined erystals. 
Covered with caustic potassa at common temperature, the benza- 
mide evolves no ammonia. Nor does its solution mingled with a salt 
of iron at common temperature give a precipitate, as indeed it in gen- 
eral gives no reaction with a metallic salt. By boiling the benzamide 
with a concentrated solution of caustic potassa, ammonia is evolved 
in abundance anda benzoate of potassa remains. By heating to 
boiling the solution of benzamide mixed with a salt of iron, it beeomes 
cloudy and throws down-a benzoate of iron. 
Vou. XXVI.—No. 2. 36 
