568 SALT AND ITS PHYSIOLOGICAL USES. 



The characteristic features of the chemical composition of these plants 

 would then be an abundance of chloride of potassium and a scarcity of 

 carbonates. 



This spurious salt tastes much like common salt, but leaves the 

 sharp after taste of potassic salts. It is not, on the whole, decidedly 

 disagreeable to a European palate; the aborigines prefer it to common 

 salt. 



The strong appetite which these sedentary, agricultural negroes have 

 for this mineral condiment quite justifies the rule established l)y 

 Bunge, according to which the need for salt is connected with agricul- 

 tural habits and vegetable diet. And if this appetite is manifested 

 here not only for true common salt but for a sort of spurious salt, the 

 law is still better exemplified. Bunge goes so far as to say that in this 

 case ol)servance of the law is carried even to aberration, but, on the 

 other hand, it will be readily seen that the theory devised l)y the 

 chemist of Basle to explain his rule is undermined by this very exam- 

 ple, for this need for salt being due, according to him, to the waste of 

 chloride of sodium from the organism, which, in its turn, is indirectly 

 caused In' aii excess of potash in the fo(i)d, should only be remedied liy 

 restoring the lost chloride. But in this case the ash salt that appeases 

 and satisfies the need is a salt of potash, and so ought, theoretically, to 

 exasperate it. 



The explanation of Bunge is therefore not tenable. All that expe- 

 rience teaches is that an exclusive vegetable diet causes a need, a par- 

 ticular appetite, which can be satisfied by substances having the taste 

 of cooking salt and containing either chloride of sodium or chloride of 

 potassium. In brief, from a chemical point of view, it is a need for 

 chlorides; from a physiological point, a need for salty savor; that is to 

 sa}", for a particular kind of gustative sensation. 



III. 



One of the efi^ects of the progress of civilization has been to sub- 

 stitute a mixed diet for that of primitive peoples, this latter being 

 sometimes exclusively animal, at others exclusively vegetable. At 

 the same time the use of salt has become general and is now a universal 

 habit, but we have just seen that its use was originally limited to vege- 

 tarian peoples and had its origin in a need either for a material con- 

 stituent of the body or for a sensation. 



Which of these two alternatives is the true one? Must we admit, 

 with Bunge, that we have a true chemical need, an appeal, an attrac- 

 tion of the organism for a substance necessary for its constitution and, 

 at the time, deficient? Is it not, rather, merely a need of the senses, 

 a sort of protest of sense against the habitual tastelessness of vege- 

 table foods which has to be remq/lied by a condiment otherwise 

 inoffensive ? 



