vin ACID- AND ALKALI-ALBUMINS 339 



or is not, and whether the jelly is transparent or is opaque, depends 

 on the concentration of the acid or alkali, and on the amount of 

 inorganic neutral salts present, as has been very thoroughly in- 

 vestigated, after Rose, by Rollet, and Zoth, and Rosenberg, and 

 Kieseritsky. 



Generally speaking, acids require to be in much greater con- 

 centration than alkalies to lead to the formation of a jelly. Pure 

 glacial acetic acid, which is neutral to litmus paper, acts on pure egg- 

 white as a dehydrating agent according to the author, 1 who finds, on 

 mixing 1 ccm. of egg-white of newly laid summer eggs with 10 ccm. 

 of glacial acetic acid, that there are thrown down large membranes 

 of a white translucent colour, which do not change their appearance 

 even if kept for months ; the albumin is hereby so completely 

 precipitated that no opalescence is seen in the mother-liquor ; 1 ccm. 

 of egg-white with 10 ccm. of a 25 per cent glacial acetic acid shows 

 a few ill-defined flocculi, while with 50 per cent acid a large number 

 .of minute membranes and transparent flocculi float about in a jelly- 

 like mother-liquor, which latter exhibits a slight opalescence. 



While, therefore, a jelly-like acid-albumin requires for its formation 

 a strong solution of acetic acid, a jelly-like alkali-albuminate may 

 be formed occasionally quite spontaneously, according to Zoth. If, 

 e.g., serum- albumin is allowed to stand, the amount of alkali which is 

 normally present in the blood-serum may suffice to convert it into a jelly. 

 On increasing the amount of alkali, the fluid solidifies more quickly, 

 and becomes also more transparent, although less firm ; a still larger 

 amount of alkali may prevent the solidification altogether. Analo- 

 gously, gelatinisation of an albumin may be prevented by too high a 

 concentration of an acid, as the latter acts either as a dehydrant, as 

 in the case of acetic acid (Mann, see above), or as a coagulant, as in 

 the case of mineral acids. Organic bases, cholin, and even urea, 

 if in sufficient concentration, also give rise to brawny jellies, according 

 to Spiro 2 and Ramsden. 3 



Kieseritsky and Rosenberg have specially studied the influence of 

 salts, and have found that no jelly is formed if by very prolonged 

 dialysis all salts are removed. They have also shown that the time 

 in which a jelly is formed and the firmness of the jelly are greatly 

 influenced by the presence of salts. These facts lead them to draw 

 an interesting parallel between the coagulation of acid-albumins and 

 alkali-albuminates and the precipitation of colloidal silicic acid in the 



1 Gustav Mann, Physiological Histology, 1902, p. 105. 



2 K. Spiro, Zeitschr.f.physiol Chem. 30. 182 (1900). 



3 W. Ramsden, Journ. of Physiol. Proceedings, 28, xxiii. (1902). 



