1920] MacDOUGAL 6* SPOEHR—AGAR 275 



of the amino acids. From these experiments it would appear that 

 the stronger the base, as indicated by its position in the electro- 



motrv 



Thus we 



have in effect K<Na<Li, and, in the weaker concentrations, 

 ethyl amine, which is a stronger base than ammonium hydroxide, 

 falling below this in hydration capacity. Interesting is the case of 

 aniline, a very weak base. Separate experiments with this sub- 

 stance were carried out, in which agar showed the following swelling: 

 in 0.01N solution, no; in 0.00 iN solution, 100; in water, 100. 

 Further investigation of the effect of a possible agar-salt for- 

 mation on the swelling was undertaken by a study of the behavior 

 of dried agar plate which had been prepared from agar previously 

 treated with KOH and NH 4 OH. Portions, of the purified agar 

 were allowed to remain in such a quantity of 0.01 normal KOH 

 and NH 4 OH solutions as to make up a 2.5 per cent agar solution. 

 After about 14 hours these solutions with the agar were heated, 

 and the agar plates poured and then dried in the usual manner. 

 The "kaliated" and "ammonated" plates thus prepared were 

 then allowed to swell in solutions of KOH, NH 4 OH, and distilled 

 water. During the first 24 hours the water in which these plates 

 had swelled became distinctly alkaline. Thereafter the water was 

 renewed every 48 hours and showed but slight alkaline reaction. 

 Thus the hydrogen ion concentration of the water in which the 

 plates had been swelled, as determined by the indicator method, 

 gave the values shown in table VII. 



TABLE VII 



Time "Kaliated" plate "AmmonatecT plate 



August 13 

 August 15 

 August 17 



10. o 



7.2 



7-4 



The figures given for August 15 and 17 probably indicate the 

 values representing the products of hydrolysis of the "kaliated" 

 and "ammonated" plates. The total swellings of these plates 

 are given in table VIII. 



From the results thus far obtained it would appear that the 

 swelling of agar in water is surpassed only by that taking place 





