200 



Voigtliiiidci' ( 1!»();») atlcinptcd to iii\-('st inalc this sni»'ges- 

 tioii. Hi' used .Malvaeeat' wliicli are known to ])v ricli in 

 mucin. Out of 71 specimens, 52 did not suhcool and tlie 

 others furnished but a very slij>ht subcoolin*;-. 



It is of interest to noliee that, accordinj^' to tlie hist men- 

 tioned authors, eoUolds favor crystallization, while niosl 

 of the physicists and biologists hold that anything which 

 delays molecular motion should prevent the formation of 

 nuclei. 



J)esi)retz (1837), assuming the possibility of inoculation 

 by the presence of a foreign body, remarked that the delay 

 in the congelation of water (subcooling) takes place as wtU 

 in a copper or in a lead container as in glass. 



The notion of impurity being conventional, the entire 

 question of inoculation by an impurity resolves itself, in 

 the last analysis, to that of inoculation by a body other tlian 

 the subcooled liquid itself. 



7. Other Factors. Among other factors which might 

 have an influence in inducing crystallization we shall men- 

 tion the cooling velocity and the concentration of the super- 

 cooled or supersaturated solutions. 



Some data on the first of these two factors will be found 

 in the work of Fiichtbauer (1904) who concludes that the 

 cooling velocity does not influence subcooling. 



According to Bakhmetieff (1901) the relation between 

 the degree of subcooling and the cooling velocity is a rather 

 complicated one. At some cooling rates there would be a 

 maximal subcooling, and at higher and lower cooling rates, 

 subcooling would be less. The author observed many ex- 

 ceptions to that "law," and he attributes them to individ- 

 ual differences or to various degrees of development of the 

 organisms investigated (insects). It seems that Bakh- 

 metieff 's notion of the method of establishing a law of 

 nature was different from that commonly accepted. 



Voigtlander (1909), from numerous experiments on 

 plant tissues, concluded that there is no relation between 

 velocity of cooling and degree of subcooling. 



Jones, Miller and Bailey (1919), working with potato, 



