140 M. MendelejefF on the Compounds of Alcohol with Water, 



author usually added a little caustic baryta, and by the yellow 

 colour the dehydration was recognized. The distillation was 

 continued with the above precautions. The first portions exhi- 

 bited too high a specific gravity ; the means were concordant 

 with each other, while the last portions had again too high a 

 specific gravity. This latter fact is due to the circumstance that 

 at a certain temperature absolute alcohol takes water from hydrate 

 of lime. 



From the numerous and concordant experiments of the author, 

 the specific gravity of absolute alcohol (water at 4° = 1) is 



078945 at 20°. 



The observations which give numbers nearest to this are those of 

 Muncke, 0*7895; Fownes, 0*78959; and Drinkwater, 0*78958; 

 while Baumhauer found 0*7899, and Kopp even 0*79277. 



By all appropriate tests the author convinced himself of the 

 complete purity of the alcohol. 



He found the boiling-point of absolute alcohol to be, as the 

 mean of three very closely agreeing numbers, 78 o, 303 (error 

 0°*01). From the tension of alcohol -vapour Regnault deter- 

 mined it at 78°*28. 



To determine the coefficient of expansion, the specific gravity 

 at different temperatures was determined. Experiment led to 

 the following formula, 



d = 0*80625 -0-000834 x *°-0-00000029* 2 , 



from which the following values are obtained : — 



Specific Gravity of Absolute Alcohol. 



At 



0*80625 



5 0*80207 



10 0*79788 



15 0*79367 



At 20 0*78445 

 „ 25 0*78322 

 „ 30 0*78096 



If, therefore, the volume of absolute alcohol at 0° 



1*0, it is at 





Gay-Lussac. 



Muncke. 



Kopp. 



MendelejefF. Baumhauer. 







10 

 15 



20 

 30 



1-01472 

 1*03094 



1-01044 

 1-01586 

 1-02138 

 103271 



1-01052 

 101585 

 1 02128 

 103242 



1-01049 

 101585 

 1-02128 

 1-03238 



1-0103 

 10156 

 10210 

 10321 



The author's numbers agree best with those of Kopp, although 

 the alcohol which Kopp used contained water. This agreement 

 is owing to the fact that, as MendelejefF found, a small addition 



