SALTS OF ALBUMIN WITH BASES 



95 



ments, such as those on electrical conductivity, electrophoresis, 

 viscosity and precipitation. The results in Table 42, p. 94, were 

 obtained with a constant concentration of albumin, the alkali 

 content being varied. 



It can be seen from these figures that, the quantity of albumin 

 being constant, the combined portion increases with increasing 

 concentration of alkali to a maximum, which then remains 

 constant in excess of alkali. One gram of serum albumin 

 combines with 0-0024 g m - equivalents of the base, a quantity 

 notably greater than the value for combination with acids, 

 which only amounts to 0-00166 gm. equivalents. Sodium 

 hydroxide, baryta, and 

 the very strong base 

 tetramethylammon- 

 ium hydroxide com- 

 bine in almost equal 

 quantities. Up to a 

 concentration of o-oi 

 N both strong and 

 weak bases combine to 



OW 



FIG. 22. 



I. Tetramethylammonium hydroxide. 

 II. Barium hydroxide. 



III. Piperidine. 



IV. Ammonium hydroxide. 



the same extent, that is, 

 practically completely, 

 with the i per cent, 

 albumin ; beyond this 

 concentration combina- 

 tion falls off with decreasing strength of base. If isohydric con- 

 centrations of base are compared, combination with the weaker 

 base is more complete, in analogy with the behaviour of the 

 protein towards acids. Thus 0-05 N NH 4 OH, with a hydroxyl 

 content of 9-3 x io~ 4 , combines with practically the same 

 quantity of albumin as a stronger base; but, in reality, 0-05 N 

 ammonium hydroxide combines with 141 x io~ 4 , or about five 

 times as much albumin as the others, if the quantity is calcu- 

 lated on the number of free OH ions present. 



It is not possible to obtain a complete view of the behaviour 

 of the salts of albumin with alkalis on ionisation owing to the 

 lack of knowledge of the cation concentration. Thus indirect 

 methods are very important in this case, as they give, when 



