56 MOLECULAR WEIGHT AND POLYMERISM 



(18-5 if instead of zT the more exact value I-98T is 

 taken), so that a one per cent, solution of methyl alcohol 

 (CH 3 OH = 32) would show a melting point # = 0-58 

 below zero, since 



xx 32=18-6 or x = 058. 



Vice versa, from a known depression of the freezing 

 point the molecular weight may be calculated, and since in 

 determining molecular weights the choice always rests 

 between values differing widely from one another, un- 

 ambiguous results may be obtained by the use of the 

 process worked out by Beckmann and Eykman. If, how- 

 ever, the object is to test strictly the formula deduced 

 above, measurement of the freezing point is found to be 

 not altogether easy. Sugar again has been the subject of 

 many experiments, and the following table shows that only 

 of late years has satisfactory agreement been reached : 



1885 Kaoult 1 .... 18-5 (i per cent.) 



1886 Raoult 2 .... 25-9 (very dilute) 

 1888 Arrhenius 3 .... 20-4 (i^ per cent.) 

 1893 Loomis* .... 17-1 (% per cent.) 



1893 Jones 5 ..... 23-7 (p. 08 per cent.) 



1894 Ponsot 6 .... 18-77 (infinitely dilute) 



1896 Abegg 7 ..... 18.6 (infinitely dilute) 



1897 Wildermann 8 . . . 18.7 (0-17 per cent.) 

 1897 Raoult 9 .... 18-72 (very dilute) 



It is especially noteworthy that Raoult, in 1897, withdrew 

 the opinion expressed by him in 1885 in favour of abnor- 

 mally great depression for sugar in very dilute solution, 

 and so fell into line with the theory of solutions. 



It should always be remembered that the formula 



A 0-02 T 2 



m = ^f 

 a 



1 Compt. Rend. 94. 1517. 2 Ann. de Chim. et de Phys. (6) 8. 313. 



3 Zeitschr.f. Phys. Chem. 2. 497. 4 Berl. Ber. 26. 800. 



5 Zeitschr.f. Phys. Chem. 12. 642. 6 Compt. Rend. 118. 977. 



7 Zeitschr.f. Phys. Chem. 20. 230. 8 Journ. Chem. Soc. Trans. 1897, p. 796. 



9 Ann. de Chim. et de Phys. (7) 10. 79. 



