286 CHEMISTRY OF THE PROTEIDS CHAP. 



If, to a solution of ammonium sulphate, of sufficient strength to 

 produce coagulation, be added equivalent amounts of tartrates, sul- 

 phates, and acetates it will be seen that, in the order given, these 

 salts show a diminishing power of assisting the ammonium sulphate 

 in bringing about coagulation. 



Tribasic-, in combination with mono- and di-basic salts, also exhibit 

 a summation of effect as is shown by the behaviour of potassium 

 citrate K 3 C 6 H 5 O 7 + NaCL 



As many neutral salts do not possess the power of causing egg- 

 white to coagulate, Pauli studied their influence on salts which do 

 coagulate, and found that magnesium and ammonium chloride, sodium 

 and potassium bromide produce a distinct increase in the coagulating 

 power of NaCl and KC1, while ammonium bromide, sodium, potassium, 

 and especially ammonium iodide markedly inhibit the coagulating 

 power of NaCl. 



Potassium nitrate increases, proportionately to the amount in which 

 it is used, the coagulating power of potassium and sodium chloride, 

 while magnesium nitrate in a normal solution and ammonium nitrate 

 are indifferent. Potassium and ammonium thiocyanates inhibit the 

 action of sodium chloride. Fluorides are especially powerful in 

 producing reversible coagulates. Arranged in the order of their 

 coagulating power, expressed in normal strengths, they are NaFl 

 (1-00); KF1 (1-25); NH 4 F1 (2'00). Potassium and ammonium 

 fluoride have their action increased by ammonium bromide, iodide 

 and thiocyanate. Ammonium chloride and nitrate do not influence 

 potassium fluoride, while they slightly increase the coagulating power 

 of ammonium fluoride, as the latter contains the same kation. 



Ammonium sulphate has its power increased by increasing amounts 

 of ammonium chloride, while increasing strengths of ammonium 

 iodide and bromide diminish the amount of coagulation. 



Potassium tartrate has its action increased by ammonium chloride, 

 sodium, and potassium bromide ; no effect is produced by ammonium 

 nitrate, while the coagulating power is diminished by ammonium 

 bromide; sodium-, potassium-, ammonium-iodides; magnesium chloride, 

 nitrate and bromide; and sodium-, potassium-, ammonium-, and 

 magnesium-thiocyanates. 



Potassium citrate is augmented by ammonium chloride and sodium 

 bromide, is left indifferent by potassium bromide, and is inhibited by 

 all other salts. 



Hofmeister was the first to state definitely that both the basic 

 and the acid radicals of salts play a part in coagulating albumin, 

 which in modern terminology means that coagulation is dependant on 



