— 52 — 
Mustard Oil. In a treatise ^) entitled "Sur le dosage de I'essence 
de moutarde", P. Roeser makes the proposal to modify Gadamer's 
method for the determination of the sulphur-content of oil of mustard 
in so far, as to determine the excess of silver nitrate in an ammoniacal 
solution, instead of an acid solution according to Volhard's method, 
as is usually done. According to this, the process should therefore 
be as follows: when the conversion of the thiosinamine with silver 
nitrate, after 24 hours' standing, has taken place, an excess of -^-^ n. 
solution of potassium cyanide is added to 50 cc of the clear filtrate, 
and the excess of potassium cyanide titrated back with -^jj n. solution 
of silver nitrate, in the presence of a few drops of a weak ammoniacal 
solution (5 per cent) of potassium iodide. Comparative determinations 
according to this method, and after Gadamer and Dieterich's 
methods, have, according to Roeser, shown no differences that were 
at all considerable. ^1 
We have not yet had occasion to make use of this modification, 
and are therefore not as yet in a position to give -an opinion about 
it, but it is our intention to try it when the opportunity arises. 
Neroli Oil (Oil of orange -flowers). The part played by the 
natural oils is now much less important than previously, as the quality 
of the artificial oil has been perfected to such an extent, that the 
former can be completely dispensed with. In order to obtain an oil 
which is at all normal, it is necessary to distil the orange-flowers either 
for the essential oil only, or only for water, and not, as is at present 
done, obtain the essential oil as it were as a by-product in the dis- 
tillation of the water, or vice versa. It wiW therefore be necessary to 
do what has to some extent already been done before, that is to say 
submit the water to cohobation until it is odourless. 
Mr. Jean Gra.s of Cannes once more communicates to us, like 
last year (compare Report October 1901, 38), a series of observations 
collected during this year's harvest of orange-flowers. We reproduce 
the interesting details in full in the table on page 53. 
'^The average temperature of May w^as much lower than in 
previous years. I believe that to this circumstance must be attributed: 
1. the somewhat smaller yield; 
2. the lower rotatory power; 
3. the higher saponification number; 
4. the solubility only in 80 per cent alcohol (last^ year the neroli 
oil was soluble in 75 per cent alcohol); 
5. the colour of the neroli oils, which is lighter than in pre- 
vious years. 
^) Journ. pharm. chim. VI. 15 (1902), 361. 
