OP ARTS AND SCIENCES. 193 



the oil under investigation, and the latter was therefore in its turn 

 identified as guaiacol. It seems to us probable that the tribrom- 

 guaiacol, which we have just described, is identical with that of 

 Tiemann and Koppe, and that the low melting point which they 

 observed was due to by-products introduced by their method of 

 preparation. A more extended investigation of the matter was, 

 however, wholly foreign to our line of work. We hope that the 

 constituents of the crude furfurol which boil above 200° may be 

 studied more fully in this Laboratory at some future time. 



Methylpyromucic Acid. 



In order to prepare from methj-lf urfurol the corresponding methyl- 

 pyromucic acid, we first attempted to follow the methods which 

 we had already used in the manufacture of pyromucic acid from 

 furfurol. We found, however, that alkaline hydrates, either in 

 alcoholic or in aqueous solution,* gave us an extremely poor pro- 

 duct in very unsatisfactory quantity. Although the experiments 

 of Lessing in the laboratory of Limpricht f upon the oxidation of 



* For many years a concentrated aqueous solution of sodic hydrate has been 

 used at this Laboratory in the preparation of pyromucic acid. Our method has 

 been, however, essentially different from that recommended by H. Schiff (Ann. 

 der Chem. u. Pharm., CCXXXIX. 374, CCLXI. 254), in that we have destroyed 

 the f urfuryl alcohol by hydrochloric acid instead of removing it with ether. The 

 saving of time and of ether has more than compensated us for the somewhat 

 diminished yield. 2 litres of furfurol are very gradually mixed with 1200 c.c. 

 of aqueous sodic hydrate (1 : 1), taking care by constant stirring and cooling 

 that the thick paste does not grow hot. On the following day 2 litres of con- 

 centrated hydrochloric acid are gradually added, the temperature toward the 

 end being allowed to rise somewhat to facilitate the complete decomposition of 

 the furfuryl alcohol. If the temperature rises too rapidly, the reaction becomes 

 violent. The furfuryl alcohol is in any case converted into a tough leathery 

 substance, which grows brittle on standing with the excess of hydrochloric acid. 

 The slightly colored mother liquor is drained off, the residue crushed in an iron 

 mortar, 4 litres of water added, and then calcic hydrate, until the solution is 

 permanently alkaline. After standing for several days, the solution being kept 

 slightly alkaline, the pyromucic acid is carried completely into solution. The 

 filtrate is but slightly colored, and this slight color may be almost wholly re- 

 moved by bone-black. The yield of nearly colorless pyromucic acid which 

 may be obtained in this way amounts to from 35 to 40 per cent of the weight 

 of furfurol taken. 



t Ann. Chem. u. Pharm., CLXV. 279. Lessing obtained a weight of pyro- 

 mucic acid equal to but 14 per cent of the weight of furfurol employed, or but 

 12 per cent of the theoretical amount. 

 vol. xxvn. (n. s. xix.) 13 



