302 CHEMISTRY OF THE PROTEIDS CHAP. 



Attempts to throw light on this question with ash-free albumin have 

 as yet led to no definite results (Pauli). 



There is, on the other hand, no difference in the order in which 

 kat-ions follow one another in the alkalies and in the alkaline earths. 

 Pauli states : " Albumin which has become changed by its firm union 

 with the electropositive-ions of the alkaline earths l differs from native 

 albumin in having its precipitation augmented by an-ions and inhibited 

 by kat-ions." Pauli points out that his explanation agrees well with 

 such other observations as those of Hardy (see p. 259), who pointed 

 out that the electrical properties of coagulated albumin are reversed 

 by changing the reaction of the medium in which it is placed ; and 

 of Posternak (see p. 282), who found the sequence of the precipitating 

 ions in acid solutions to be the opposite from that which Hofmeister 2 

 and Pauli had determined for native albumin, etc. 



The effect of adding alkali-salts to the salts of the alkaline earths 

 Pauli has summed up thus : " The greater the precipitating power of 

 the an-ion of the alkaline earth which we add to an albumin solution, 

 the less will be the increase in the amount of the precipitate which we 

 obtain by adding an alkaline salt with a feebler an-ion, and the inhibi- 

 tory effect of the alkali-ions (i.e. kat-ions) may make itself felt beside 

 the relatively small number of the earthy alkali kat-ions [as for example, 

 in 1 normal Ca(CNS) 2 ]. The reverse holds good if the an-ion of the 

 alkaline earth has a low precipitating value, while that of the added alkali 

 has a high one, and if the number of the simultaneously acting kat-ions 

 of the alkaline earth be great, as it is, for example, in 9 normal CaCl 2 ." 



Pauli has also studied the effect of adding hydrochloric acid and 

 caustic potash to the various salt solutions he used for coagulating and 

 precipitating egg-white. 3 To exclude the formation of acid-precipitates, 

 stronger solutions than 0'03 normal HC1 were never used, especially 

 as O'Ol normal HC1 strongly reddens litmus. It was found that the 

 mono-, di-, and tribasic neutral salts of the alkali metals were not 

 appreciably influenced by 0*01 normal HC1. 4 With 0'02 normal 

 HC1, the sulphates of Na, K, NH 4 , and Mg produce a somewhat 

 quicker, and with - 02 normal NaOH a somewhat slower, coagula- 



1 The double electrical load is not sufficient to explain the behaviour of the ions of 

 the alkaline earths towards albumin, for the divalent magnesium behaves like the alkalies, 

 while the monovalent lithium in many respects approaches the alkaline earths, for its 

 bromide precipitates, and the compounds formed thereby soon become irreversible. 



2 Hofmeister, Arch. f. experim. Path. u. Pharm. 25. 26. 27. 



3 Coagulation and precipitation are terms used in the author's sense (see p. 272). 



4 In every case 2 ccm. of egg-white and 8 ccm. water were taken, and the salts then 

 added in the solid form. It was necessary to at once mix the egg-white with the rest of 

 the fluid to avoid alterations in the concentration of the electrolytes. 



