— 7 o — 



the acid contained in oil of hyssop to be 1-pinonic acid, and the 

 ketone 1-pinocamphone. 



We cannot omit here to lay stress upon the fact that the former 

 practice of neglecting to observe the rotation of the primary material 

 has helped to delay very considerably the solution of certain problems 

 existing in connection with the pinene series. It will be advisable, in 

 the case of future examinations, either to start with entirely inactive 

 pinene, or to use as primary material substances of the highest 

 degree of optical purity obtainable. For instance, it is stated in the 

 literature on the subject that active oil of turpentine yields racemic 

 pinol hydrate, but when we used highly active pinene, active pinol 

 hydrate, m. p. 150 , was very easily formed. 



In a discussion on the investigations of essential oils published 

 during the year 1908, Jeancard and Satie 1 ) refer among other mat- 

 ters, to our statements as to the constants of hyssop oils distilled by 

 us 2 ). For purposes of comparison they set out the properties of two 

 oils which they had obtained at Cannes in 1903 and 1908 from green, 

 flowering herb. These oils deviated very greatly from our distillates 

 as regards rotation and solubility. Their behaviour was as follows: — 



Distillate 1903: d 15 o 0,9252, «d -)- i° acid no. 0,8, ester no. 9,2, 

 ester no. after acetylation 70,0. 



Distillate 1908: di 5 o 0,9262, ^ D — 2°6', acid no. 0,8, esterno. 1 1,9, 

 ester no. after acetylation 51,1. 



The constants observed by us in our own distillates were as 

 follow: — 



di 5 o 0,925 to 0,940, «d — 17 to — 24 18', acid no. up to 3,1, 

 ester no. 1,4 to 11, ester no. after acetylation 37 to 45. 



Our distillates required from 1 to 8 vols, of 80 per cent, alcohol 

 to give a solution, and this solution was not even then always quite 

 clear, owing to the separation of paraffin, but the oils obtained by 

 Jeancard and Satie were soluble in 70 per cent. (2 to 2,5 vols) and 

 65 per cent. (8,5 to 9 vols) alcohol respectively. The last-named point 

 of difference may possibly be due to the manner of distilling, but as 

 regards the great difference in rotation we are at present at a loss 

 for an explanation. Jeancard and Satie ascribe it to the fact that they 

 used fresh, whereas we used withered for material distilling. This ex- 

 planation is contradicted by the observation made by us that there is 

 not the slightest difference in constants between oil from quite fresh 

 and from faded herb. We therefore think that an explanation of the 

 differences must rather be sought in botanical differences between the 

 plants distilled. 



1 ) Americ. Perfumer 4 (1909), 84. 



2 ) Report April 1908, 58. 



