72 



brown, tasteless, almost free from ash, soluble in alcohol and in 

 ether, and had the composition represented by the formula 

 C 5 4 H 3 5 Oii + i to 6 HO (C = 6); i.e., C^H^O^ + i to 6 

 H 2 O, the quantity of water increasing according to the number of 

 precipitations with water. From this resin various copper com- 

 pounds were prepared: C 54 H 35 O 1:L CuO ; C 54 H 35 O 1:L 2CuO and 

 C 54 H 38 14 CuO. 



For the isolation of hop bitter, LERMER 1 proceeded in quite a 

 different fashion. 



He extracted fresh hops with ether, treated the ether residue 

 with 90 per cent, alcohol, in order to separate " Myricin " (wax), the 

 latter remaining undissolved, and after removal of the alcohol, 

 again dissolved the residue in ether. The ethereal solution was then 

 repeatedly shaken with strong potash lye, whereby the bulk of the 

 non-crystallisable resinous bodies was removed, passing into the 

 aqueous layer. The ethereal solution, which exhibited strong 

 alkaline reaction owing to the presence of potash, was repeatedly 

 shaken up with water, when the hop bitter passed into the aqueous 

 layer. From this the bitter substance was isolated by addition of 

 copper sulphate solution, which produced a blueish precipitate, 

 consisting of microscopically small needles, which could be washed 

 with small quantities of ether. In larger quantities of ether the 

 precipitate was completely soluble, a proof that it contained no 

 cupric hydrate. 



From this copper compound of the hop-bitter principle (it loses 

 its fine blue colour rapidly when dried), LERMER separated the 

 bitter substance itself by decomposition with hydrogen sulphide 

 in ethereal solution. The ethereal solution so obtained, when 

 evaporated in a current of carbon dioxide, leaves a brownish, 

 syrupy residue, in which after 12-24 nour s ray-shaped crystals 

 begin to appear, and continually augment until the whole solidifies 

 to a crystalline mass. The crystals are, however, still contaminated 

 with more or less brownish resin, the separation of which presents 

 great difficulties. There is only one solvent, nitro-benzene, which 



1 Dingier' s Poly technisches Journal, 1863, 169, 54. 



