71 



PELLETAN, 1 PAYEN, and CHEVALIER prepared this substance by 

 treating an aqueous hop extract with lime and alcohol, evaporating 

 the alcohol, extracting the residue with water, again evaporating 

 and extracting with ether. The aqueous solution of this bitter 

 substance (a yellowish white body, rather more soluble in warm 

 than in cold water) exhibited neutral reaction, and was not 

 decomposed by acids or alkalies. 



In DOEBEREINERS' 2 German Apothecaries' Manual a similar 

 process for obtaining the bitter substance from an aqueous extract 

 is described. The body is stated to be soluble in five parts of 

 boiling water, more soluble in alcohol, and almost insoluble in ether. 

 Further, that it is destroyed on heating, without formation of 

 ammoniacal products. 



PERSONNE S claimed to have discovered a bitter substance of 

 alkaloidal nature (precipitated by tannic acid, iodine in potassium 

 iodide, &c.), but was unable to effect its isolation in a pure state. 



J. C. LEUCHS 4 made various experiments concerning the de- 

 bittering of hop extracts, by treating aqueous solutions of the same, 

 with freshly ignited wood charcoal, almond water, and almond 

 paste. An extract of hops in boiling water was completely de- 

 bittered on addition of acetic acid, or tartaric acid, lemon juice, 

 sulphurous acid, aldehyde, or formic acid, and the same result 

 obtained on prolonged exposure of the extract to air at io-i5 R. 

 (54-5-6575 F.). 



VLAANDEREN S attempted to obtain the resin by extracting lupulin 

 with spirit. To this end, he repeatedly precipitated the alcoholic 

 extract with water, redissolved the separated resin in alcohol, 

 and again precipitated with water, thinking by this means to 

 get rid also of the hop oil. The ' resin finally obtained was dark 



1 Journal de Pharmacie, Tome 8, 209. 



2 Deutsches Apothekerbuch, III, 1847, 636. 



3 Comptes Rendus, 1854, 39- 



* Journal fur Praktische Chemie, 1867, 101, 137. 



5 Scheikundige Verhandelungen en Ondevzoekingen, van G. T. Mulder, Deil II, 

 Bladz 87, 1858; abstracted in Jahresbericht fitr Chemie, 1858, 448. 



