CHEMICAL CHARACTERS OF OTTO. 171 



Otto of Kose, it is well known, consists of two bodies, a 1859. 

 liquid essential oil or elseoptene (upon which I have made no 



experiments) and a stearoptene. The stearoptene I find to be, and 



, , ,,. , , Stearoptene. 



when pure, a colourless crystallizable substance, devoid of 

 odour and taste, fusing at 95 F., very slightly soluble in alcohol 

 of sp. gr. *838 in the cold, but more soluble if heated. It is 

 soluble in the liquid portion or elseoptene of Otto of Eose, but, 

 according to its abundance, separates more or less readily with 

 a depression of temperature. It dissolves readily in ether, 

 chloroform, or olive oil, but not in solution of potash or 

 ammonia. 



These two bodies, the elseoptene and stearoptene, exist, 

 according to my observations, in the Otto of different districts 

 in very different proportions, and to their relative amounts I 

 attribute much of the variation which I find in the specimens 

 examined. The amount of stearoptene was determined in a Determina- 

 series of parallel experiments, conducted simultaneously by ~, tion f 

 treating a given weight of Otto with alcohol (sp. gr. '838), 

 throwing the precipitated stearoptene upon a filter and 

 thoroughly washing it with fresh alcohol; the same amount 

 of alcohol being employed in each case. The stearoptene was 

 then pressed for some days between paper, and after exposure 

 to the air and drying over oil of vitriol, was weighed. 1 The 

 fusing-point was determined in each case by the same ther- 

 mometer placed by the side of the bottle, and the observations 

 were confirmed by repeated trials. 



The English and French samples experimented upon were 

 obtained direct from the manufacturers, and mostly upon my 

 personal application. The Turkish sample No. 7 was manu- 

 factured at Kizanlik, where Messrs. Herman, from whom I 

 received it, have an establishment. 



certainly, of the absence of rotatory power in the Idris Yaghi, but one 

 which it is fair to mention. 



1 I am quite aware that this method of determining the amount of 

 stearoptene is not free from objection, since, the more abundant the 

 elseoptene, the less will the stearoptene (in which it is soluble) be precipitated 

 when the Otto is first treated with alcohol. 



