346 



FOOD AND FOOD ADULTERANTS. 



Benedikt and Zsigmondy, and used it on saponified fats. It has never 

 been applied to wine or beer, so far as I know. 



Legler J Las formulated a method, intended, as the author says in his 

 paper, to supply the place of the method of the Berlin committee, and 

 atone for its deficiencies. It depends on the oxidation of glycerine to 

 carbonic acid by means of sulphuric acid and potassic bichromate. 2 The 

 estimation of organic bodies by the oxidation of their contained carbon 

 has been proposed and carried out by Cross and Bevan 3 who operate in 

 a dry, and by Burghardt, 4 who operates in a wet, way. The operation 

 was performed by Legler in a Will's carbonic acid apparatus, as follows : 



The air flask contains the glycerine mixed with a saturated solution of potassic 

 dichromate; the other contains, as usual, strong sulphuric acid. After the apparatus 

 has been weighed, a little air is drawn out which causes some of the acid to mix with 

 the chromate. A regular evolution of carbonic acid soon sets in, but must be assisted 

 towards the last by gently boiling. The flask containing the sulphuric acid must be 

 kept cool. When no more gas bubbles are formed, the apparatus is cooled by partial 

 immersion in cold water, and the remaining carbonic acid is expelled by a current of 

 dry air. The apparatus is now reweighed and the loss represents carbonic acid. The 

 following equation shows the action taking place : 



One part of glycerine therefore requires about 7.5 parts at K 2 Cr 2 07 and 10 parts 

 of H 2 SO4, but an excess of each is of course used- 



The mode of procedure in operating on wine is as follows : The crude glycerine 

 obtained from lOOcc. of wine, after evaporation with 3cc. milk of lime and 2 grams of 

 quartz, and extracting the mass with alcohol of 9G per cent., is, after weighing, di- 

 luted up to a definite bulk, and aliquot parts are taken for the ash and the oxidation 

 process. A white wine, containing 8.54 per cent, alcohol and 2.07 per cent, solid 

 matter, gave in lOOcc. 1.4 grams crude glycerine, with .1278 grams ash, 25cc. of the glyc- 

 erine diluted up to 50cc. yielding .725 gm. COi = 1.10 per cent, glycerine. A dupli- 

 cate experiment gave 1.47 crude glycerine with .136 ash, .710 COj = .99 per cent. 

 glycerine, the average thus being 1 per cent. 5 and the relation between alcohol 

 and glycerine as 100 : 11.7. 



Estimation of glycerine in wine after it has been purposely added. 



Three lots of lOOcc. each of the same wine were mixed respectively with .125, .250, 

 and .500 grams of glycerine, and analyzed as before. The results were as follows : 



Allowing for the 1. per cent, of natural glycerine in the sample we obtain .115, .254, 

 and .492 per cent, of glycerine. 



1 Rep. Anal. Chem. 6, GUI ; Analyst 12, 14. 

 2 Chem. N:\VH 53, 297; also 55, 2. 

 :> Chem. News 55, 34 ; see also 55, 40. 



Tlie average is really 1.05 per cent., which would mako some dilleronco in the 

 figures wliieli follow. 



