466 Prof. Liebig 07i the Constitution of 



nor any salt formed of an alkaline base and an acid which 

 might be destroyed in the organism, by the vital process, and 

 thus cause the alkaline base to be liberated. The blood must 

 contain the same salts as exist in the aliments. With the ex- 

 ception of common salt, nothing is added during the digestion 

 of the aliments. We have seen that this substance undergoes 

 decomposition in the upper part of the digestive apparatus, 

 being resolved into free soda and free hydrochloric acid ; but 

 we have also seen that the liberated soda rejoins the hydro- 

 chloric acid during the preparation of the chyme, and previous 

 to the transformation of the latter into chyle ; that is, when 

 the acid has performed its function, namely, the solution of 

 the aliments; the salt formed by this combination, that is, 

 common salt, has neither an acid nor an alktvline reaction. 

 The salts with alkaline reaction contained in meat, flour, or 

 grain, are alkaline phosphates. It is obvious that the alkaline 

 reaction of the chyle, lymph, and blood of animals feeding 

 upon animal and vegetable substances, can only be derived 

 from their alkaline phosphates. The serum of the blood can 

 only be considered as a combination of albumine with an alka- 

 line phosphate ; the fibrine of the blood, or the fibrine of the 

 muscular fibre, is a combination of albumine with phosphate 

 of lime. 



The bibasic phosphates of soda and of potash are, in many 

 respects, highly remarkable salts; although of a tolerably 

 strong alkaline reaction, yet they exercise no destructive ac- 

 tion upon the skin or upon organic formations ; they possess 

 all the properties of the free alkalies without being such; thus, 

 for instance, they absorb a large amount of carbonic acid, and 

 this in such a manner that acids produce effervescence in a 

 saturated solution of this kind, just as they would in alkaline 

 carbonates; they dissolve coagulated curd of milk or cheese, 

 as well as coagulated albumen, into clear fluids with the 

 greatest facility, just as caustic or carbonated alkalies do. But 

 of still greater importance in relation to the secretion of urine 

 is their deportment towards hippuric acid and uric acid. Hip- 

 puric acid dissolves with the greatest facility in water to which 

 common phosphate of soda has been added ; uric acid pos- 

 sesses the same property at a high temperature ; the phosphate 

 of soda, in this process, loses its alkaline reaction completely 

 upon the addition of uric acid and hippuric acid, and assumes 

 an acid reaction. The acid nature of the urine of man, and 

 of the carnivorous and graminivorous animals, is thus ex- 

 plained in a very simple manner. 



There are but two principal channels through which the 

 salts entering the organism with the aliments can effect their 



