276 HOPS. 



ing the development of mould fungi, except such as are 

 anaerobic (capable of existing without oxygen). 



Dr. Naumann and Pohl recommend sprinkling the hops 

 with very strong alcohol before pressing. Satisfactory results 

 attended the experiments made with this method at Weihen- 

 stephan.^ 



A proposal to preserve hops by heating the pressed mass 

 to 100° C. has also been mooted ; and Wrighton advocated 

 compressing undried hops in air-tight receptacles ! 



The necessity for an improved method of preserving hops 

 has repeatedly generated the idea of recovering the active 

 ingredients of hops by extraction and employing the extract 

 as a hop substitute. 



Newton employed gasoline for this purpose ; and 

 Lawrence, after experimenting with various solvents, fixed 

 upon petroleum spirit (ether). Fruwirth reports that this 

 method is used on a large scale by the New York Hop 

 Extract Company of Waterville, and that the product is 

 employed by brewers in the United States. 



Percy and Wells ^ used a mixture of alkali and water, the 

 extract being then concentrated by steam heat and mixed 

 with saccharose. Salley (New York) preserves the hop 

 extract by means of alcohol. 



Boule and others propose to remove the lupulin by 

 mechanical treatment, and, after extracting the bracts with 

 boiling water, evaporate the solution to dryness and incorporate 

 it with a suitable proportion of the lupulin, the product 

 being then packed in tins and used in place of hops. 

 According to Van Laer ^ this method is pursued in Belgium. 



The method introduced by Breithaupt of Hagenau has 

 met with some attention in Germany. This consists in 

 extracting the hop oil by alcohol and preserving the residual 



^ Leyser and Heiss, Die Bierhrauerei, Stuttgart, 1893. ^ Ibid. 



2 Zeitsch/rift fil/r das geswmmte Brauwesen, 1898, No. 34. 



