— 103 — 



Analytical notes* 



By employing the methods of Thorpe and Holmes 1 ), Allen 2 ), 

 and the Association of Official Agricultural Chemists of 

 America 3 ), E. A. Mann 4 ) has determined the alcohol - content of 

 essences, and has found that all three methods give the same results 

 as when the alcohol-content of the distillate is ascertained pycnometric- 

 ally. In the author's opinion the American method is to be preferred 

 in many cases on account of its simplicity, but clear distillates are 

 not always obtained, and the same remark applies to Allen's method. 

 Thorpe's determination is without doubt the most certain one, but 

 it requires a little more time than the others. 



J The procedure in the above-named methods is as follows : According 

 to Thorpe and Holmes, ioo vol. water are added to 25 vol. of the 

 sample, the mixture is saturated with salt, and shaken for 5 minutes 

 with 70 vol. petroleum ether (b. p. below 60 °). After separating off the 

 aqueous layer, the petroleum ether is vigorously shaken with 25 vol. 

 of a saturated solution of salt. The aqueous portion is now added to 

 the original one, and of the total quantity 100 vol. are carefully distilled 

 over. The alcohol -content of the distillate obtained has to be mul- 

 tiplied with 4. — According to Allen the sample is diluted with water 

 to the 8 -fold quantity, calcium chloride and sodium biphosphate added, 

 100 vol. filtered and distilled. The alcohol - content of the distillate 

 ascertained has to be multiplied with 8. — The method of Associa- 

 tion of Official Agricultural Chemists of America requires the 

 addition of the 3 -fold quantity of water to the sample in question, 

 and further the addition of magnesium carbonate. After shaking, 

 100 cc. are filtered off and distilled. The alcohol- content found must 

 then be multiplied with 4. 



On the reaction of phenyl hydrazin with the aldehydes and ketones 

 contained in essential oils Benedikt and Strache 5 ) have founded 

 a method for determining quantitatively the carbonyl - group of these 

 bodies. The method is based upon the oxidation of the non-combined 

 phenyl hydrazin with F eh ling's solution, and measurement of the 

 nitrogen evolved. This method which, as far as we know, has not 

 been introduced in the technical industries, has recently been modified 

 by Watson Smith jun. 6 ) in so far, that for driving over the 

 • nitrogen no longer steam is used, but a current of carbonic acid 



1 ) Journ. Soc chem. Industry 22 (1003), 232. 



2 ) Commercial Organic Analysis. 3 rd Ed ., 1, 162. 



3 ) Bulletin 46, U. S. Department of Agriculture, and Food Analysis und In- 

 spection, Leach. 



4 ) Journ. Soc. chem. Industry 24 (1905), 1284. 



5 ) Monatsh. f. Chem. 14 (1893), 273. Ace to Chem. Centralbl. 1893, II. 168. 



6 ) Chem. News 93 (1906), 83. Ace. to Chem. Centralbl. 1906, I. 1289. 



