t w i» distinct phases in i lie solutioi . 



between the two, because of tl 



ticle, is an enormous surfaci 



and at tlic interface beta een th< the pi 



depend on surfac< . surface tens 



developed, and are responsible for the peculiar | 



solutions as compared with those of molecular 



therefore, be Btj led honwg< in I 



which we have hitherto been concerned with, 



r>ct\\ ecu these i w o groups of solutions is an interim i 

 susp s' 'as suspensions of quartz or carbon, or oil i 



sides being turbid in transmitted light, the Bolutioi 



means of the ultramicroscope i atain partic I 



rated by filtration from the fluid they are 



case of many emulsions in which the parti 



through the filter pores by changing their shap 



centrifuged suspensions may also separate inl 



though this can be greatly hindered by the addition o ling 



substance such as gelatin or certain bodies 1 



tive action i as peptone, prol 



True Colloidal Solutions 



1. The Solution Is More or Less Turbid. Frequently th 



nized by holding the solution in a thin-walled - rt a 



dark background, bul the turbidity may 1 



for its detection the use of the Tyndall phenomenon. 1 



to all in the effect of a beam of sunlight let in through a small a] 



into an otherwise darkened room. In the coura 



.lust particles, which are invisible in an equally illumi 



come visible, and thus render very distinct tl 



If a colloidal solution contained in a glas iral- 



lel sides, is held in th w such a beam, 



will be Been in the Liquid, which is qoI tl • with n 



Focused artificial lighl may be employed for ii 



The lighl that is sent OUt at righl an-_ 



which means that the particles reflecting th< r than 



the mean wave length of the light f< •* 3 



Btood that the individual particli 



visible t<> the naked eye by the beam, although i 



often he seen |i\ USlIlg !' I luillil: 



scope combined w ith suitable m; 



2. Colloids Do Not Readily Diffuse, i 



