Separation of Three Liquids by Fractional Distillation. 25 



distillate collected in receiver No. 5 until the temperature 

 again rose to 71 o, 0, when it was replaced by receiver No. 8, 

 and the distillation was continued until the temperature rose 

 to 77°'l. The third fraction from I. (No. 11, B. P. 77°'8 to 

 89°*2) was then added to the residue in the flask, and the 

 distillate collected in No. 8 until the temperature again rose 

 to 77°*1, when No. 11 was put in its place. When the tem- 

 perature had risen to 84°*4 a new receiver, No. 13, was sub- 

 stituted for No. 11, and the distillation was continued until 

 the thermometer registered 91°'7. The last fraction from I. 

 (No. 14, B.P. above 89°* 2) was then added to the residue in 

 the flask and the distillate collected in No. 13 until the tem- 

 perature rose again to 91°*7, after which fractions were col- 

 lected in No. 14 from 91°'7 to 98°*4, and No. 15 from 98°-4 

 to 101 o, 5, when the distillation was stopped, and the residue 

 poured into receiver No. 17. 



The third fractionation (III.) was carried out in a similar 

 manner, a new fraction No. 3 being collected at the beginning. 

 As the temperature rose to 101 o, 55, the true B.P. of propyl 

 acetate, before the end of the last distillation, the residue in 

 the flask consisted of this substance in a nearly pure state, and 

 it was therefore collected in a separate flask Z, and was not re- 

 distilled during the preliminary fractionations. The residues 

 from the subsequent fractionations up to the tenth were col- 

 lected in Z, but after this, as a large amount of propyl acetate 

 had been removed, the temperature did not reach 101°'55, 

 and the residue from the eleventh fractionation (B. P. above 

 101 o, 45) was collected in a new flask, Y. 



At the end of the twelfth fractionation the temperature 

 rose only to 101°* 15, and the residue was therefore placed in 

 a third flask, X, and subsequently the residues were collected 

 in W, V, &c, to Q, as shown in the tables. 



It was not until the fifth fractionation that the first fraction 

 began to boil at 57 0, 1, the B.P. of methyl acetate, and it 

 was not thought advisable to separate the first portion of the 

 first distillate until the eighth fractionation. This portion and 

 also the corresponding ones up to the twentieth fractionation 

 were collected together in flask A, after which the first 

 portions were collected in B, C, D, and E. 



The ratios — — give an indication of the purity of the 



various distillates, for with a pure substance, since A£ = 0, 



-r— =*> , while with a very impure substance there is a rapid 



