170 OTTO OF ROSE. 



1859. identifying it with the Eoske Oil that is imported from Bombay ; 

 and when we consider the immense influx of pilgrims every 

 year to Jeddah, the transport of the drug northward to Egypt 

 and Turkey is easily explained. 



Although I have thus demonstrated (as I think) the identity 



of the Turkish Idris Yaghi with the EoshA Oil of Bombay, 



arid therefore proved them the produce of one or more species 



of Andropogon, growing in India, it may be proper that I should 



Idris Oil not briefly state other reasons for considering that this volatile oil 



l Oil of^Jera* 1 ^ as no c ^ m * ^ e Dame often given to it of Essence of Geranium. 



nium. I may say, then, that it differs from true essential Oil of Geranium, 



such as is distilled from a variety of Pelargonium Radula, Ait., 



in the South of France. 



1. In odour. 



2. In optical properties, in having (according to the observa- 

 tions of my friend Dr. De Vry) no rotatory power when 

 examined by polarised light, whereas, French Oil of Geranium 

 possesses the power of right-handed rotation. 1 



3. In chemical properties, inasmuch as when exposed to the 

 vapour of iodine, it does not acquire the intense coloration that 

 occurs when Oil of Geranium is so treated. 



4. In commercial value, true Oil of Geranium being worth 

 six times the price of Idris Yaghi, and ten times that of the 

 Bombay Hoshe* Oil. 



Before being mixed with Otto, the Idris Yaghi is subjected 

 by the Turkish dealers to some purifying process, chiefly, it 

 would seem, with a view to diminish its colour, a pale colour 

 in Otto of Rose being deemed a sign of goodness. 



CHEMICAL CHARACTERS OF OTTO OF ROSE. 

 As I have already observed, there exists regarding the tem- 

 perature at which Otto of Rose liquefies, great discrepancy 

 between the statements of authors and the result of observations 

 made upon the Otto of commerce. 



1 But, as some essence of geranium from Algiers, examined by the same 

 observer, was found to have the power of left-handed rotation to an almost 

 equal extent, it is obviously possible that by mixing the two, an essence 

 having no rotatory power might be produced an improbable explanation, 



