541 



datiscine which has produced it, I have not the least doubt that silk 

 dyers, who may hereafter employ solutions of datisca cannabina, will 

 find it highly advantageous to convert their datiscine into datiscetine 

 by boiling it with dilute sulphuric acid. 



Oil of the Ptychotis Ajowan. 



The Ptychotis Ajowan is an umbelliferous plant well known in 

 India for its aromatic and carminative properties. When its seeds 

 are distilled with water they readily yield between five and six per 

 cent, of an essential oil resembling in smell that of oil of thyme. 

 When this oil is left in shallow vessels to spontaneous evaporation 

 at low temperatures, it deposits a large quantity of beautiful crystals, 

 which are identical with the stearopten brought from India by the 

 late Dr. Stocks, and described by me in a short notice in the De- 

 cember Number of the ' Pharmaceutical Journal' for 1854. 



The crude oil was rectified, and the portion which came over 

 between 160 C. and 164 C. was collected separately and carefully 

 rectified over sodium. Its boiling-point was found to be 172 C., 

 and its composition isomeric with oil of turpentine, namely 



C 10 H 8 or C^ H 16 . 



The stearopten obtained from the less volatile portion of the oil 

 was purified, and formed large flat rhombohedral crystals, which have 

 been carefully measured by Professor Miller of Cambridge. When 

 subjected to analysis it gave the formula 



C^H^orC^H^HO. 



In the notice of the stearopten of this oil which appeared in the 

 ' Pharmaceutical Journal,' from the examination of the small 

 quantity then at my disposal, a different formula was deduced, 

 which I now withdraw, and substitute the preceding formula, 



When the crystalline stearopten is digested for eight or nine 

 days with the strongest nitric acid, it is gradually converted into a 

 crystallizable acid, apparently containing no nitrogen. This acid 

 is but slightly soluble even in boiling water, but is deposited in 

 needles on the cooling of the solution. It is very soluble in alcohol 

 and ether, from which it is deposited in crystals. Both its silver 

 and its baryta salts are crystallizable, and appear very stable. It 



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