ROSACEZ. aoe, 
top; fruit ovate, pulpy; calyx and peduncles glgndulosely 
hispid, viscous ; colour of flower light red. 
Chemical composition.—Pure oil of roses carefully distilled is 
at first colourless, but quickly becomes yellowish. Its spe- 
cific gravity at 22°-9 CO. is ‘870 and its boiling point 228°8 C., 
it solidifies at 11°] to 10°1 C., and is soluble in absolute 
alcohol and in’ acetic acid. (Brannt.) Rose oil is a mix- 
ture of a liquid constituent containing oxygen, anda hydrocar- 
bon or stearopten, C" H%", which is not altered by boiling with, 
alcoholic potash, and which is entirely destitute of odour. From 
the Turkish oil it may be obtained to the extent of 12 to 14 per 
cent., in the German oil it is present to the extent of 32 to 34 
per cent. The liquid portion of Rose oil has not yet been 
_ obtained entirely free from the stearopten. ‘To isolate the 
_. Stearopten, Messrs. Schimmel heated fifty grams of oil with 500 
grams of 75 per cent. spirit to a temperature of 70° to 80° C., 
upon cooling, the stearopten separated almost entirely. It 
was then removed from the liquid and treated similarly with 
200 grams more of 75 per cent. spirit, and this operation 
was repeated until the stearopten was obtained perfectly — 
odourless. : 
Rose oil, from which the stearopten has been removed in 
the above described manner, is perfectly liquid at 0° C.; but 
when placed in a cooling mixture it solidifies to a gelatinous 
Mass, showing that it is not quite free from stearopten. 
This liquid oil is described as having an extraordinarily fino — 
and powerful odour, and as presenting the advantage that 
when used dissolved in spirit it does not give rise to any 
crystalline separation. 
If cautiously melted by the warmth of the sun, the stearop- 
ten forms on cooling, microscopic crystals of very peculiar 
Shape. Most of them have the form of truncated hexahedral 
pyramids, not however belonging to the rhombohedric system, 
as the angles are evidently not equal; many of them are oddly 3 
curved, thus §. Hxamined under the polarizing microscope, 
_ these crystals from their refractive power make a brilliant 
oe ; 
