— 47 — 
few months, there is no prospect during this season of an accumulation 
of such large stocks as was the case last year, — a factor which may be 
of importance in view of the annual increase of the world's consumption. 
The citral-determination of lemon oil. 
The question regarding the citral-content of lemon oil, to which 
we have already referred in our last Report (page 34), has led to some 
further publications with which we will deal briefly in the following pages. 
Berte^), who had stated already before Gulli and Stavenhagen 
that lemon oil contains about 6,5 ^/^ citral, again takes this matter up, 
and strongly advocates the use of the estimation-method published by 
him in conjunction with Soldaini, a process which we have already 
discussed in previous Reports, and of which we have there also given 
a detailed description 2). 
Parry against this, maintains his previous statements that lemon 
oil contains at most 3 ^j^ citral, and points out that otherwise the citral- 
content of terpeneless oils would be decidedly higher. 
Kremers and Branded) also discuss this subject. Their work is 
of special interest, inasmuch as it supplies a very noticeable contribution 
to the history of all methods for citral-determination recommended up 
to the present. We have dealt with the individual processes already 
in our Reports, in some cases in great detail, with the exception of 
the one which has been published quite recently by Sad tier, and to 
which we return further down. We can therefore refer in this connection 
to our previous publications and also to Kremers and Brand el's work. 
But the authors also mention their own experiments on this subject; 
they have carried out citral-determinations partly by the bisulphite 
method, and partly by the method recommended by Sad tier, in 
which in the one case a 5 ^/q solution of citral in limonene was used, 
and in the other a natural lemon oil. 
The bisulphite method recommended by Kremers and Bran del 
is as follows: 
5 cc oil are placed in a cassia flask and 25 cc sodium bisulphite 
solution (30^/0) added, and the mixture maintained on the water-bath 
at a temperature of 60° for half an hour, with frequent shaking. It 
is then left to cool, after wich distilled water is gradually added up 
to the mark, the mixture being each time shaken. The content of 
percentage by volume is then determined in the usual manner. 
The results thereby obtained by Kremers and Bran del agree 
well in some respects, but the limits thus obtained differ by 3 to 4%; 
^) Chemist and Druggist 63 (1903), 752. 
2) Report April 1897, 18; 1900, 22. 
^) Chemist and Druggist 63 (1903), 820. 
^) Pharm. Review 22 (1904), 15, 72. 
