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METHODS OF ANALYSIS OF DISTILLED SPIRITS. 

 By L. M. TOLMAN and W. E. HILLYER. 



The methods of the association for the analysis of distilled spirits, as given in 

 Bulletin 107, Revised, of the Bureau of Chemistry, are for the most part the best 

 methods available; but a few modifications and some new methods have been found 

 to be of value. 



DETERMINATION OF COLORING MATTERS. 



The method which has proved to be the most satisfactory in the Bureau of Chemistry 

 for distinguishing between natural and artificial coloring matters in distilled spirits 

 is the qualitative Marsh test. This depends on the relative solubilities of coloring 

 matters in ethyl alcohol, amyl alcohol, and water. The addition of amyl alcohol, 

 when in sufficient quantity, to a mixture of 50 parts of ethyl alcohol and 50 parts 

 of water will cause a separation of the liquids into two layers, the lower layer being 

 largely water and the upper one a mixture of ethyl alcohol, amyl alcohol, and some 

 water. As a result of this separation, water-soluble coloring matter can be separated 

 from alcohol-soluble coloring matter; that is to say, caramel can be separated from 

 the natural coloring matter of whisky. Up to the present time this has been used 

 as a qualitative test of the greatest value, but it now appears that the method can 

 be adapted for quantitative determination, the amount of added coloring matter 

 present in relation to the natural coloring matter being determined. The following 

 method has been developed and found to be entirely satisfactory: 



AMYL INSOLUBLE METHOD (QUANTITATIVE MARSH TEST). 



Evaporate 50 cc of the whisky just to dryness on the steam bath in a porcelain 

 evaporating dish. Add 26.3 cc of 95 per cent alcohol to dissolve the residue, and 

 transfer to a 50 cc flask, using water and making up to volume with water. This 

 gives a 50 per cent alcoholic solution from which to make an extraction. [It is nec- 

 essary that the extraction should be made from a solution of definite alcoholic 

 strength, as it can be readily seen that variations in the percentage of ethyl alcohol 

 would make a decided difference in the amount of amyl alcohol to effect the proper 

 separation.] Place 25 cc of this 50 per cent alcoholic solution in a separatory funnel, 

 add 20 cc of the Marsh reagent, then shake lightly so as not to emulsify. (The Marsh 

 reagent consists of 100 cc of amyl alcohol, 3 cc of sirupy phosphoric acid, and 3 cc 

 of water; shake before using.) Allow the layers to separate; repeat this shaking and 

 standing twice more, and after the layers have clearly separated the last time, draw 

 off the lower or water layer containing the caramel or water-soluble coloring matter 

 into a 25 cc cylinder and make up to volume with 50 per cent alcohol. Compare 

 this portion in a colorimeter with the remaining 25 cc which has not been treated 

 with the Marsh reagent, thus directly giving the percentage of color not soluble in 

 amyl alcohol. 



The following table gives the results obtained by applying this method to straight 

 and imitation whiskies: 



Amyl alcohol tests for color in whiskies. 



