— 154 — 



The following experiments in separation were carried out in a similar { 

 manner: — 



To a mixture of 127 g. acetic acid and 274,4 g. toluene Golodetz added 

 67 g. water (minimum boiling point of the mixture of water and toluene 

 81,4°, proportion 19,6% water). Fractional distillation gave for the 

 highest boiling fraction 64 g. pure acetic acid = 50,2% of the quantity 

 present in the mixture. 



242 g. toluene mixed with 60 g. benzene were diluted with 39,5 g. methyl 

 alcohol (b. p. 64,7°) (minimum boiling point of the mixture of methyl 

 alcohol and benzene 58,35°; proportion 60,45% benzene). After fractional 

 distillation 228,5 g. pure toluene was obtained, t 



Also: 



36,3 g. benzene, b. p. 80° ) minimum b. p. of the mixture 58,35°, 



23,7 g. met hyl alcohol, b. p. 64,7° J proportion benzene 60,45%; 

 .„* t j. t t • i t as rs \ minimum b. p. of the mixture 38°, 



170 g. carbon disulphide, b. p. 46° ( proportion methyl alcohol 12 _ 130/o . 

 Result: 23 g. pure benzene = 63,4 %. 

 Also : 



45 g. ethyl butyrate, b. p. 119,9° 



15 g. amy l bromide, b. p. 118,5 to 119° 



39 g. ^-propyl alcohol, b. p. 9 7,2° I minimum b. p. of the mixture 94°, 



Result: 30 g. ethyl butyrate = 66,7%. J Proportion propyl alcohol 70,770. 



The experiments mentioned by the author are only intended to explain 

 the method; it is not claimed that they are all of practical usefulness. 



The method of separation by distilling, making use of the minimum b. p., 

 was known 1 ). But to Golodetz belongs the merit of having again illus- 

 trated by striking examples this property of numerous mixtures which is 

 so little used in practice. 



At the conclusion of his paper the author states "from all the above 

 experiments it is evident that the mixtures which boil without decompo- 

 sition behave like uniform chemical entities; a fact which has already been 

 pointed out by Makowiecki." 



The fact that a distilled solution possesses a constant temperature 

 and a constant composition of steam does not of itself warrant the con- 

 clusion that it represents a chemical compound. It is only when the boiling 

 point is also a maximum boiling-point that the presence of a molecul^ 

 chemical compound may be assumed with certainty. The only exception 

 to this rule which is at present known is a solution of formic acid in 

 water which, although the melting-point curve shows a maximum b. p., 



x ) v. Rechenberg, Gewinnung und Trennung der atherischen Ole durch Destination. Grund- 

 ziige einer allgemeinen Destillationslehre. 1910. p. 593. 



