vin THE FORMATION OF IRREVERSIBLE SALTS 303 



tion than with native albumin. After twenty-four hours no difference 

 could be seen between the tubes which had HC1 and KOH added and 

 the control tubes. All precipitates were found to be reversible. 



Using 6-normal solutions of non-coagulating electrolytes (Mg, NH 4 , 

 K, Na acetates, chlorides, nitrates, bromides, iodides, and thiocyanates) 

 acidification with O'Ol normal HC1 converted only the thiocyanates 

 and iodides into precipitating agents : Mg > NH 4 > K > Na. The pre- 

 cipitates were irreversible. On gradually increasing the amount of 

 acid the chlorides, nitrates, and bromides also become precipitants, but 

 ammonium salts do not precipitate till the acidity has reached 0'03 

 normal HC1. 



Keeping the acidity 0'03 normal HC1 constant, and increasing the 

 concentration of salts, Pauli found the precipitating power of the 

 salts, arranged according to their an-ions, to follow in this order : 

 CNS>Br>N0 3 , S0 4 , while, arranged according to their kat-ions, he 

 obtained the series Na>K>NH 4 >Mg. 



Chlorides do not increase in the same ratio as do the other neutral 

 salts, because the chlorides interfere to a certain extent with the 

 electrical dissociation of the HC1, as both possess the Cl-ion in 

 common. If the chlorides are only in strengths of 0'25 and 0*5 

 normal, the kat-ions form again the series Na>K>NH 4 >Mg, while 

 in higher concentrations (1-normal) the order of the kat-ions is inversed 

 and becomes the same as if only 0*01 normal HC1 were present, 

 showing that 1-normal chlorides greatly reduce the electrical dissocia- 

 tion of the HCL. 



With '03 normal HC1 the precipitation, on increasing the amounts 

 of the salts, reaches a maximum, and then sinks on the further addition 

 of salt. Using equivalent solutions the maximal precipitation of the 

 egg-white was not always obtained with the same concentration of 

 different salts. All precipitates on being diluted were found to be 

 irreversible. 



The acetates, fluorides, tartrates, and citrates of the alkalies, 

 instead of producing an increased precipitation in the presence of 

 HC1, were found to diminish the amount of the precipitate. 



7b. Compounds of Albumins with the Heavy Metals 



The following historical review is based on the papers by 

 Vaubel, 1 Schulz, 2 and Galeotti. 3 The first metallic albuminate 



1 W. Vaubel, Journ. /. prakt. Chem. 60. 55 (1899). 



2 Fr. N. Schulz, Die Grosse des Mweissmolekiils. Jena (1903), Gastar Fischer. 

 3 G. Galeotti, Zeitschr. f. physioL Chem. 40. 492 (1904). 



