I 3 



( 



54 



THE BEGINNINGS OF II FE. 



om 



IS 



which prevails — an arrangement, however, which by 

 the mere influence of physical conditions, the molecules 

 of certain crystalloids are known <^ spontaneously ' to 

 assume. A further consequence directly flowino- fi 

 this superior complexity of the colloid molecule 



J J 



as we have previously endeavoured to show, the o-reater 

 instability which characterizes them as a class. Very 

 . slight changes in the conditions or influences to which 

 the colloid is exposed lead to changes in its constitu- 

 tion — owing to the ease with which a re-arrangement 

 is brought about amongst its constituent atoms or 

 elementary molecules. Its very existence, as Prof. 

 Graham pointed out, is one of ^continual metastasis' 

 and ' may be compared in this respect to water while 

 existing liquid at a temperature under its usual freezing 

 point, or to a supersaturated saline solution.' 



Colloids, like crystalloids, are soluble — sometimes 

 largely so— though generally ^they are held in solution 

 by a most feeble force.' The feeble force with which, 

 when in the state of solution, their molecules are com- 

 bined with those of water, is another peculiarity emi- 

 nently favourable to the occurrence of rearrangements 

 or recompositions amongst their molecules. Thus 

 when in a state of solution colloids are most favour- 

 ably situated, in all respects, for undergoing whatever 



changes the incidence of physical forces is capable of 

 effecting. 



It will be well now to enquire a little more fully 



#■ 



nature 



ail 



tlie 



■) 



'd^'') 









form i^ 



under whicl 

 substance: 



of such a 



s 



are onlj seen in 



dt up of ^^^ 

 in a cryst 



which h 



precipitate had bee 



' Tlie conditions unde 



Ws Mnmr^ of ( 



'istalhe state, its part 

 "is fluid state is 



'iM. Someti] 

 * * ias no de& 



spontaneously 



*Cti0tt 



■■ ^* the liquid ' 

 arrangem 



or 



Q 



S ■ ■ ""H be, 



Sti...'>°n, 



H 



«to 



'nto 



'^■stalliz 



^^e Hq„:; 



quic 



eb 



yc 



