383 



From this solution 40 cm', was taken with a pipette. I let it flow 

 into a 50 cm*, flask, added a fixed quantity of the aminoacid in 

 question to some of the flasks and added at the same time different 

 volumes of a solution of sodium hydroxide of known strength. 



Finally the liquids were diluted with H,0 to 50 cm\ and 

 shaken thoroughly. The thus obtained solutions were placed in a 

 thermostat with waterjacket (temperature .*i4°), the temperature of 

 the liquid in the flasks therefore rising gradually. At the beginning 

 of the experiment and later from time to time the polarisation and 

 the intensity of colour of the solutions were deteimined under 

 comparable circumstances. The results of these observations are found 

 in table I. (See table on the following page). 



P^-om the results mentioned in this table it follows in the first 

 place that the aminoacids in question piactically do not influence 

 the polarisation of glucose (polarisation of Nrs. 6, 7 and 8 at 

 beginning). 



After 372 hours the polarisation has diminished most in the flaaks 

 that contained the largest quantity of NaOH (Nrs. 5 and 9 : -j- 4°, 6 V.). 



Although the added number of cm', of the NaOH-solution with 

 the Nrs. 6, 7 and 8 is equally great as that with the Nrs. 5 and 9, 

 it follows from the table that the polarisation with 6, 7, and 8 has 

 diminished only to respectively 6,5, 6,6, and 6,5. 



This number is less than that of N". 3 to which 3 cm', of the 

 NaOH-solution had been added. We may therefore conclude that 

 two milligram molecules of each of the aminoacids compensate the 

 action of about 2 cm', of 1,06 normal NaOH-solution. The intensity 

 of colour too of Nrs. 6, 7, and 8 (after + 21 and 6 X 24 hours) 

 that lies between that of Nrs. 3 and 4 was herewith in agreement. 



The «-aminocompounds of butyric acid, isovaleric acid and 

 isocaproic acid therefore behave in alkalic solution as about mono- 

 basic acid. 



Behaviour in acidic solution. 



The inversion of sucrose by hydrochloric acid was likewise 

 prevented by the said three cr-aminoacids. 



From the results united in table Wa and II/> especially from the 

 polarisation at the beginning of the ex[)eriments it follows that these 

 three aminoacids neither influence to ar) important degree the 

 polarisation of sucrose nor change polarisation of the solution by 

 their own optical activity. 



Whilst the polarisation after addition of 5 cm' 1,01 normal hydro- 

 chloric acid after 16'/, hours (Table II") has lowered lo respectively 



