THE ALUMNI JOURNAL 3 



The crystals are waslied with ethyl alcohol and the filtrate replaced 

 in the freezing mixture when a second crop of crystals are obtained, 

 which may be filtered on the first, and the whole thoroughly washed 

 with strong ethyl alcohol. 



The crystals are then dried, dissolved in the least possible amount 

 of chloroform, and hot methyl alcohol added until recrystallation 

 stars ; finally the crystals are filtered ofif, and mounted in olive oil for 

 examination under microscope. 



The composition of Oil of Lemon, as given by several authors and 

 essential oil experts, is as follows : 



Citral, Phellandrine, Limonene, Octyl and Nonyl aldehydes, Geranyl 

 Acetate, Geranoil, IMethyl Anthranilate, Citrannol, and a resin and some 

 claim Pinene. 



The most important of which is Citral, Cc, H,5 COH. There are 

 several methods for the determination of this substance, none of which 

 is of any degree of accuracy. The following are some which have 

 been tried and judged inaccurate: 



(i) By the formation of a soluble sulfonic acid with sod. sulfite, 

 using rosalic acid as an indicator. 



Q H,, COH + 2Na3 SO, + 2H, O = Co H,, COH (NaSOg) 

 o+2NaOH. This is the U. S. P. method. 



(2) By the condensation compound formed with cyanacetic acid 

 in alkaline solution: 



Co U,, COH -f CH, CNCOOH = Co H,, CHC^^^qqjj+H.O. 



(3) By the formation of an oxine with hydroxylamine in alcoholic 

 solutions, and titrating excess of hydroxylamine : 



Co Hi,5 COH + H, NOH = C, H,, CHNOH -f H. O. 



There are other methods, such as the bisulphate method, the coloro- 

 nietric method, which is based on the aldehyd reaction produced by 

 mixing it with fuchsine sulfurous acid. 



(To be continued in the next issue.) 



P. S. — The part of the definition relating to the first 10% distillate 

 should be changed, as I have since investigated and could not find an 

 oil that would rotate less than 2°. This statement is verified by a well- 

 known chemical house. 



