120 



mentioned that the method could be applied both to aliphatic and 

 to aromatic aldehydes, and in a recently published work 1 ) he discusses 

 the subject still further. He found from subsequent experiments that 

 the method is suitable for saturated and unsaturated aldehydes of the 

 aliphatic as well as the aromatic series. Moreover, some ketones also 

 react well with sodium sulphite, above all carvone, which quantitatively 

 gives accurate results, whilst others, for example Japan camphor 2 ), do 

 not combine at all with sodium sulphite. Sad tier believes that in 

 such cases double-linkings, or certain atom-groups, play a part. 



The chemical processes which take place during the conversion 

 are explained by Sad tier by the following formulae: 



i. for aldehydes: 

 R • CHO + 2Na 2 S0 3 + 2H 2 = R- CH : (NaS0 3 ) 2 + 2NaOH + H 2 0, 



2. for ketones: 

 R.CO -R + 2Na 2 S0 3 + 2H 2 = R 2 : C : (NaS0 3 ) 2 + 2NaOH + H 2 0. 



In our previous Report we already referred to the difficulties 

 which titration offers in the case before us, and at the present moment 

 we are not yet convinced of the suitability of this method for the 

 citral-determination in lemon oil. 



A further treatise, dealing with the same method of estimation, 

 originates from H. E. Burgess 3 ). His method differs from Sad tier's 

 chiefly in the fact that the determination is purely volumetric. Burgess 

 employs a small flask of 200 cc. capacity of which the neck carries a 



scale of 5 cc. divided in — , and which is moreover provided at one 



10 



side with a tube reaching to the bottom of the vessel, for the intro- 

 duction of oil, reagents, and water. In this flask 5 cc. oil are mixed 

 with a saturated solution of neutral sodium sulphite and two drops 

 phenol phthalein solution, and heated on a water-bath. The mixture 

 is repeatedly thoroughly shaken, and the liberated alkali neutralised 

 from time to time with dilute acetic acid (1 : 10), until the red coloration 

 has permanently disappeared. Water is then added to bring the oil 

 in the neck of the flask, and when cold, the scale is carefully read. 

 The quantity of oil absorbed, when multiplied with 20, gives the 

 percentage of aldehyde or ketone. 



It is claimed for Burgess' process that it has this advantage over 

 the bisulphite method, that it takes up less time, and that the end 

 of the reaction can be accurately observed. Moreover, it is said that 



1 ) Journ. Soc. chem. Ind. 23 (1904), 303. 



2 ) Sadtler designates it incorrectly as an isomer of carvone; the latter has 

 the formula C 10 H 14 O, whilst Japan camphor has C 10 H 16 O. 



3 ) The Analyst 29 (1904), 78. 



