Distillation of Binary Mixtures. 



529 



reduction any particular distillate is considered to correspond 

 with the mean condition of the liquid before and after its 

 separation therefrom. 



If the process above sketched could be absolutely relied on, 

 it would be possible, starting with a strong spirit in the 

 retort, to obtain from one distillation data relating to a great 

 variety of strengths. But this method is not to be recom- 

 mended, as the errors would tend to accumulate. The first 

 50 c.c, condensed under somewhat abnormal conditions, was 

 not used directly, but only to allow for the change going on 

 in the retort. The 2nd, 3rd, and 4th collections were usually 

 calculated so as to show the strengths of these distillates in 

 comparison with that of the liquid, but they were regarded 

 rather as checks upon one another than as independent results 

 relating to an altered state of affairs. 



Observations 



sufficient to giy 



Alcohol and Water. 

 upon mixtures of water 



and ethyl alcohol, 

 a nearly complete curve, were made in 1891 

 and again in 1898 with good general agreement. The 

 specific gravities were found in the balance with a bottle of 

 20 c.c. capacity, and the calculations of strength were by 

 Mendeleef's tables with appropriate temperature correction. 

 The results of the second series are given in the accompanying- 

 table and are exhibited as a curve, A, in fig. 3. The strengths 

 are throughout reckoned by weight. 



Date 

 1898. 



Strength 



of ' 

 Liquid. 



Strength 



of 

 Vapour. 



May 4 



•01970 



•03982 



•0601 



•0988 



•2586 



•4562 



•6606 



•7739 



•8221 



•8594 



•9241 



•9555 



•1750 

 •3159 

 •3979 

 •5145 

 •6803 

 •7412 

 •7976 

 •8414 

 •8622 

 •8849 

 •9284 

 •9545 



„ 3 



„ 5 



„ 9 



„ 10 



„ 13 



„ 16 



„ 17 



„ 20 



„ 23 



„ 24 



„ 25 





The observation of May 4 thus signifies that to a liquid 

 containing by weight 1*97 per cent, of alcohol there corre- 

 sponds a vapour containing by weight 17*5 per cent, of 

 alcohol. From the results of Slay 24 we see that when the 

 liquid reaches 92 per cent, the vapour is but little the stronger, 



