VITAL PHENOMENA 69 



hydration of N0 3 ' is small, of CI' is greater and of SO/' is 

 greatest, but the other members do not fall in order, from the 

 available data. Their effect in salting out poorly soluble sub- 

 stances increases from left to right. 



The ionic speed of the cations increases in the order : Li, Na, 

 NH 4 , K, Rb, Cs (the viscosity of their aqueous solutions de- 

 creases in same order), and the order, Mg, Ca, Sr, Ba. They 

 accelerate the hydrolysis of esters by acids from left to right. 

 The reverse is true of the hydrolysis of esters by bases. Solu- 

 tions of KNO3, KC1, CsCl and RbCl are less viscous than water. 

 The electrolytic solution tension decreases in the order Li, K, 

 Na and Ba, Ca, Mg, Sr. 



The heavy metals are poisonous on account of their low elec- 

 trolytic solution tension, as will be discussed later. 



The H and OH ions are distinguished by their very high ionic 

 speed and relatively low electrolytic solution tensions. They are 

 very active and distinguish the acids and bases. 



Non-Electrolytes 



The dissociation of the so-called non-electrolytes is so small 

 as not to affect the osmotic pressure. The H ion dissociation 

 and effect on surface tension of many of them has been given. 

 Many of these substances may be salted out of solution by the 

 addition of electrolytes. The order of effectiveness of ions is : 

 CNS <I, CIO,, N0 3 <Br <CI <OH <S0 4 <C03, and H 

 <Cs <Rb <NH 4 <Li (hydr.) <K <Na. The same holds 

 true for salting out dissolved gases, which may be included under 

 the non-electrolytes. 



Many electrolytes and colloids may be precipitated from their 

 water solutions by non-electrolytes. According to one view this 

 is the substitution of one solvent for another. Salt is more 

 soluble in water than in alcohol, and when alcohol is added to 

 its saturated aqueous solution some salt is precipitated. 



According to Traube the precipitating power of non-electro- 

 lytes is proportional to their effectiveness in lowering the surface 

 tension of water. The following table gives their power of pre- 

 cipitating Li 2 C0 3 as compared with the surface tension of their 

 .25 mol solutions at 15 : 



