PREC1PITANTS FOR FURFURAL 



45 



TABLE I. 

 BARBITURIC ACID. 



*Precipitated with a little more than the theoretical amount o£ bar- 

 bituric acid. 



**Precipitated with 4 times the theoretical amount of barbituric acid. 



***Precipitated with 16 times the theoretical amount of barbituric 

 acid. 



From the above table it is at once apparent that the results 

 with barbituric acid are uniformly low. The last three deter- 

 minations show the effect of increasing amounts of the precipi- 

 tant. With barbituric acid and furfural in molecular propor- 

 tions of sixteen to one, the result is nearly quantitative. This 

 observation is in accord w T ith statement of Unger and Jager that 

 eight times the theoretical amount of barbituric acid is necessary 

 for complete recovery of the furfural. 



TABLE II. 



THIOBARBITURIC ACID. 



♦Precipitated at 60°. 



With thiobarbituric acid, as shown in the above table, the pre- 

 cipitation is quantitative without using a large excess of the 

 reagent. The results tend even to run just a trifle over the 



