OBSERVATIONS AND EXPERIMENTS ON ROSE OIL. 149 
are informed by Hanbury, as well as by Baur, that it is a liquid volatile oil 
which is chiefly used for the adulteration of attar. 
I fully agree with these authors and others that the stearoptene does not 
possess the smell of roses. Not only is it devoid of that, but upon being heated 
it emi ts a very offensive odour, exactly like that of heated fat or wax. All observers 
attributing any rose odour to this stearoptene must have had it in an imper¬ 
fectly purified state. If the stearoptene is repeatedly dissolved in chloroform, 
and precipitated by spirit of wine, and finally heated at 212° F. for some hours, 
it wili be obtained entirely odourless at the ordinary temperature, smelling only 
when heated as above stated. 
According to an analysis made lately by Mr. Stierlin, one of my pupils, the 
composition of rose-stearoptene agrees indeed with the formula C„H n . Mr. 
Stierlin found—Carbon. 84-96 per cent. 
Hydrogen .... 14-54 ,, 
Whether C 16 1I 16 as proposed by Blanchet, is the true formula or not, cannot yet 
be determined ; it may as well agree with C n H n+2 . This is of secondary im¬ 
portance for the moment, and requires many further researches. 
I wished to know the density of the vapour of the stearoptene, but it does 
not support a sufficiently elevated temperature without decomposition. Its be¬ 
haviour is exactly like that of wax ; it does not sublime, but slowly ascends the 
walls of the vessel, and takes a brownish hue. At 90° to 91° F. (32-5° C.) it 
melts ; at 276° F. (150° C.) vapours are evolved ; at 496° F. (272° C.) it begins 
to boil; at 500° F. (275° C.) the whole mass is boiling, and turns brownish; 
at 546° F. (300° C^ blackish. 
These facts are striking enough, considering that the stearoptene is obtained by 
submitting ro&es to the usual distillation, and show evidently the effects of the 
diffusion of vapours. In this respect I cannot agree with those observers who say 
that, on paper, the stains of rose-oil disappear quickly. This is not possible 
whenever the oil contains much stearoptene ; and a paper on which I caused some 
pure stearoptene to melt did not lose the stain on exposure to the heat of the 
water-bath for some days. A mixture of bichromate of potassa and sulphuric 
acid does not manifestly react upon it, yet a light odour somewhat resembling 
acroleine appears to prove that some reaction must take place. 
Potassium does not alter the melted stearoptene; when heated with dry 
caustic potassa a slight smell of mace is evolved ; but benzol removes nearly all 
the stearoptene unaltered from the melted mass. If this is neutralized with sul¬ 
phuric acid, no fact showing any action of the potassa on the stearoptene is 
observed. 
These experiments prove that the behaviour of rose-stearoptene is well in 
accordance with its composition, and that it is a very stable body. Fuming 
nitric acid, even in large quantity, does not energetically attack it. But if this 
reaction is continued for some days, the fuming acid always being maintained 
at 212° F., the stearoptene gradually diminishes. The best way of promoting 
the oxidation is to place the two liquids in a large glass tube immersed verti¬ 
cally in boiling water, and to shake it frequently. The tube terminates in a 
sharply-pointed end, which I cover with cork. The latter retains the nitric 
vapours without any danger, as the cork is easily thrown off if their tension be¬ 
comes too strong. The top of the tube may be a little curved downwards, in 
order to prevent the products of the reaction of the air upon the cork from 
being washed into the tube. 
When after some days the stearoptene has entirely disappeared the liquid is 
perfectly clear while hot, but always becomes somewhat turbid on cooling, 
though without separating any oily drops. It is then heated to 212° F. in a 
small glass retort until all the nitric acid has distilled. In the liquid coming 
over, the smell of butyric acid cannot be mistaken, and several trials have 
