534 



Lord Bayleigh on the 



Sulphuric Acid and Water. 



The distillates were here determined chemically. From 

 acid in the retort of less strength than 60 per cent, the dis- 

 tillate failed to redden litmus. From 75 per cent, acid the 

 distillate contained about one-thousandth part of H 2 S0 4 . 

 From 81 per cent, the distillate contained 1*6 per cent. ; 

 from 90 per cent, the distillate contained 7*1 per cent. ; and 

 from 93 percent, liquid the distillate contained J 2*8 per cent, 

 of acid. The curve is given in D, fig. 4, the dotted portion 

 for strengths of liquid greater than 93 per cent, being con- 

 jectural. 



Acetic Acid and Water. 



This case was examined as likely to exemplify a very 

 different behaviour from any of the others, since it was 

 known that these substances are not easily separated by dis- 

 tillation. The retort was charged with 1000 c.c. of mixture 

 and two distillates were collected of 150 c.c. each. The 

 analyses were conducted chemically and the results calcu- 

 lated as already explained. Thus the first distillate was con- 

 sidered to correspond with the mean strength in the retort 

 before and after its separation. The following were the 

 results obtained : — 



Acetic Acid and Water. 



Date 

 1902. 



Strength of 

 Liquid. 



Strength of 

 Vapour. 



Aug. 18 



•0677 

 •1458 

 •2682 

 •3746 

 •4998 

 •6156 

 •7227 

 •8166 

 •9070 



•0510 

 •1136 

 •2035 

 •2810 

 •3849 

 •4907 

 •6045 

 •7306 

 •8622 



Aug. 11 





Aug. 18 



Aug. 5 



Aug. 23 



Aug. 22 



Aug. 2L 



Aug. 20 



It appears that the vapour is always weaker than the 

 liquid, but that the difference is never great. A plot of the 

 corresponding strengths is given in C (fig. 3, p. 530). 



In illustration of the preceding theory an experiment was 

 tried in which three-quarters of the original volume of liquid 

 was distilled over. The original liquid consisted of 1000 c. c. 

 of acid of density 1*010, and of strength (as determined 

 chemically) '0757, representing as usual the proportion of 

 the weight of acetic acid to the whole weight. The residue 



