INORGANIC SALTS 177 



proteinates must co-exist in certain definite proportions 

 in the cell-structures, including the membranes, if 

 certain biologically necessary physical properties are to 

 be preserved. Substitution of Na for Ca compounds 

 would occur in pure Na salt solutions, with resulting 

 structural changes which might well be injurious or fatal. 

 Clowes^ has recently shown that salt-antagonisms 

 having an even closer resemblance to biological salt 

 antagonisms may be demonstrated in oil- water emulsion 

 systems by varying the proportions of Na and Ca soaps 

 in the interfacial films. The number of separate drops 

 formed when a slightly alkaline salt solution is allowed 

 to flow through a stalagmometer into oUve oil is found 

 to vary in a remarkable manner with variations in the 

 proportions of NaCl and CaCL in the solution; thus 

 with an alkaHnity of .ooin NaOH, the following number 

 of drops per minute were observed with different 

 solutions : 



c- , ,. Drops per 



Solution ^yiinute 



Control (no salt) 44 



Pure 0.15 m NaCl 300 



Pure 0.0015 m CaCL 24 



0.15 m NaCl-ho.0015 m CaCL 44 



0.3 m NaCl-ho.003 m CaCL : 43 



0.4s m NaCl-ho.005 m CaCL 43 



0.6 m NaCl-f-o.oi m CaClj 43 



The pure NaCl solution greatly promotes the 

 tendency toward fine subdivision of the drops; the 

 CaCL decreases this tendency; at a certain ratio of the 

 two salts (Na: Ca about 50 or 100:1) the two tendencies 

 counteract each other. The result depends on the 



^ Clowes, Journal of Physical Chemistry, XX (1916), 407. 



