APPENDIX A. 377 



most general and striking property of the majority of bop substitutes is tbe intensity 

 of their bitter taste, a character which materially increases the difficulty of detecting 

 them, owing to the very moderate amount employed to give the beer the desired 

 flavor. There is one other complication of practical importance, and that is the very 

 considerable quantity of beer usually recommended to be used for the analysis. 

 Thus, if two liters be used for the main examination, as is recommended by Dragen- 

 dorff, at least twice that quantity should be submitted to the analyst, and hence 

 twelve liters would have to be purchased. The necessity of purchasing so large a 

 quantity as two and a half gallons of each beer would almost certainly render the act 

 abortive. 



In looking into the question, therefore, I have aimed at reducing the amount of 

 beer employed as low as possible. 



In the last number of the Analyst I gave a list of references to articles iii English 

 periodicals, &c., connected with detection of hop substitutes in beer. These I have 

 carefully studied, and they have formed the foundation of the following statements 

 and proposals : 



Dragendorft', who has published a very elaborate method for the recognition of a 

 large number of possible hop substitutes (Jour. Chem. Soc., XXVII, 818; XLII, 103), 

 operates on two liters of beer, precipitates the concentrated liquid with basic acetate 

 of lead, further concentrates the filtrate and adds a large volume (1,000 to l,200cc.)of 

 absolute alcohol. The spirit is subsequently driven off, and the various principles 

 extracted by a systematic employment of immiscible solvents. 



Wittstein (Jour. Chem. Soc., XXIX, 767) operates in a similar manner, but works 

 on one liter, and omits the treatment with acetate of lead, as indeed did DrageudorfF 

 in his older method. In the method described by me in my Commercial Organic 

 Analysis (Vol. I, page 97), based on a process of Euder's, one liter of beer is employed, 

 the concentrated liquid is treated with alcohol, the filtrate precipitated with ether, 

 and the filtered liquid evaporated, the residue redissolved in alcohol, treated with 

 water, and the solution precipitated with acetate of lead. 



Several of the writers on the subject state that on precipitating a beer with basic 

 acetate of lead the hop-bitter is wholly precipitated, and hence, if the concentrated 

 filtrate still have a bitter taste, the presence of some hop substitute is certain. 1 



This difference seemed to me so important that I have very carefully investigated it, 

 and find it perfectly in accordance with the fact. I prefer, however, to employ neutral 

 acetate of lead instead of the basic or ammouiacal acetate, as the latter reagents are 

 liable to precipitate certain bitter principles not removed by the first. On the other 

 hand, the hop-bitter is very perfectly precipitated by neutral lead acetate, and this 

 statement is equally true of an infusion of hops purposely prepared and of a beer in 

 which hops is the sole bitter used ; but I have some reason to think that basic acetate 

 of lead is liable to effect a less perfect separation of the hop-bitter. 



In attempting to improve these processes I have endeavored to dispense with the 

 use of alcohol, and yet separate the bitter principles from the sugar and other bodies 

 which disguise the bitter taste and interfere with application of chemical tests, and 

 find that a very satisfactory product for further treatment can be obtained by the fol- 

 lowing simple method : 



One liter of the beer is evaporated to about SOOcc. and is then precipitated, while hot , 

 with a solution of neutral acetate of lead. The precipitate is filtered off, the filtrate 

 allowed to become cool, and any further precipitate is also removed. The excess of 

 lead is then removed from the filtrate by sulphuretted hydrogen, and the liquid fil- 



'This distinction between the bitter principles of hops and hop substitutes is re- 

 ferred to in the work entitled Chemistry Applied to the Arts and Manufactures, edited 

 by Chas. Vincent, and often described as the New Edition of Muspratt's Chemistry. 

 The process is also described in Wyuter Blyth's work on the Analysis of Food, and 

 forms an essential part of Ender's method of detecting bitter substances, so that there 

 is a very general consensus of opinion as to the value of the test. 



