2 9 — 



increased production of concentrated oil of lemon. According to 

 Berte, even slight adulterations of lemon oil with oil of turpentine or 

 lemon oil terpenes can be detected by means of the method recommend- 

 ed by himself and Soldaini, by which 5O°/ of the oil are distilled 

 off and the rotations of the oil, the distillate, and the residue are 

 compared with each other. This method is said to be decidedly more 

 useful, especially in the case of oils adulterated with lemon oil ter- 

 penes, than the method recommended by us (test of the first io°/ 

 of the distillate) by means of which even an adulteration with 15% 

 terpenes cannot be recognised. 



Berte has, in the manner indicated above, distilled pure as well 

 as purposely adulterated lemon oils, and arrived thereby at the following 

 results : 



a D20° 



of 



the distillate 



(5°%) 



a D20° 

 of the re- 

 sidue 



Pure lemon oil 



with 5°/ Americ. turpentine oil 

 „ 5% French „ „ i) 



» 5% lemon oil terpenes 



TO / 



lemon oil terpenes .... 



■62° 4 o' 



■59°4o' 



•57°45' 



•63 



■63°2o' 



• 66° 



+ 63° 45 

 -|-59 30' 

 + 57 c 



IO 



+ 6 3 °icv 

 -j-63°2cv 

 4-6o°io' 



6l°20 



59°2o 

 f56°3o 

 — 62°4o 



63°25 

 --70 20 



According to these results, the distillate of pure oil has a slightly 

 higher rotatory power than the original oil, whilst the rotation of the 

 residue is correspondingly lower. With adulterated oils the conditions 

 are somewhat different. In the case of the grosser adulterations the 

 differences naturally become more pronounced; small admixtures (as 

 the results quoted show), cause but very slight differences, and it is 

 questionable whether it is possible on the strength of the condition 

 of the distillate, to arrive here in every case at a definite conclusion 

 on the quality of the oil. 



Contrary to Berte, we have even found no difference whatever 

 between pure oil and oils adulterated with a small quantity of lemon 

 oil terpene, when we repeated the tests according to Berte' s method. 

 We added to a lemon oil 1 o °/ lemon oil terpenes as obtained by 

 us as a by-product in the manufacture of concentrated lemon oil, 

 and tested the pure oil and the adulterated one in the manner indi- 

 cated by Berte: 



1 ) It is clear that in consequence of the distillation carried out at ordinary 

 pressure, decompositions occur, as otherwise it would not be possible to explain that 

 both the distillate and the residue have a lower rotatory power than the original oil. 



