ioo COLLOID CHEMISTRY OF THE PROTEINS 



tions of alkali. It is analogous to the precipitation by excess 

 of acid. 



Table 47. 



Ox-serum Albumin 1*03 per cent. 

 with various Alkali Concentrations. 



When strong bases of these concentrations are employed, 

 complete formation of an alkali albuminate undoubtedly occurs 

 eventually, but it is open to question whether the precipitate 

 formed immediately is already a denatured product of some sort. 

 The idea that it is the neutral portion of a protein salt which is 

 precipitated by excess of alkali seems to meet this case as well. 

 On standing for some time, decomposition of the precipitate 

 sets in, it decreases in quantity, and finally dissolves completely. 



The precipitation of albumin by alkali is notable in two ways. 

 The product, which easily agglomerates to fibrous curds, differs 

 from that of precipitation by acid in so far as it is easily soluble 

 when water is added. In the second place, the precipitation by 

 alkalis is but little affected by temperature changes over a 

 considerable range, whereas the precipitation by concentrated 

 acid is greatly favoured by rise in temperature, perhaps owing 

 to an increase in the rate of the secondaty and irreversible 

 change in the albumin. In the case of weaker bases like 

 piperidine and methylamine, the precipitate of serum albumin 

 appears as an opalescent ring when a layer of the base is run on 

 to serum albumin solution. Still weaker bases, such as tri- 

 ethylamine and trimethylamine, fail to give the reaction at all. 



