CHLORIDE OF SODIUM. 241 



salt to the animal organism cannot therefore be questioned, and 

 its importance is further shown by the fact, that during fasting, or 

 when there is a deficient supply of nutriment, in diseases, as 

 pneumonia, &c., the separation of common salt by the urine soon 

 ceases, whilst in those cases in which the blood is deficient in this 

 substance, all the chloride of sodium entering the organism from 

 without is retained until the normal amount is restored. 



We have now, however, to consider the more difficult question 

 of the manner in which chloride of sodium contributes towards 

 the metamorphosis of animal matter. We have endeavoured to 

 refer the importance of this salt to the peculiar relations which it 

 exhibits towards the albuminous matters of the blood and of the 

 animal body generally ; and it seemed to us that its special use 

 may be to dissolve the pure albumen (or serum-casein of Panum),* 

 together with the albuminate of soda, and thus render it amenable 

 to chemical agencies. Liebig has, however, drawn attention to 

 a very important fact connected with this subject. Gluten is 

 dissolved as readily as muscle-fibrin in water containing hydro- 

 chloric acid (see page 84), and is precipitated from this 

 solution not only by more hydrochloric acid, but also by the 

 addition of a solution of chloride of sodium of less strength even 

 than 4|-. From these and similar experiments we may assume 

 that the amount of common salt in animal fluids exerts a certain 

 influence on the separation as well as the solution of albuminous 

 substances, although we are unable to demonstrate the individual 

 details with any great exactness. 



The mode of action of chloride of sodium in the metamorphosis 

 of animal matter was the more difficult to determine, as it was 

 known to the chemists as an extremely indifferent substance, with 

 very little tendency to form further chemical combinations, urea 

 and grape-sugar being almost the only substances with which it 

 combines chemically. These two facts sufficed, however, to lead 

 Liebig to a very ingenious view regarding the function of this 

 substance in the metamorphosis of matter. It is very probable 

 that the union of urea with chloride of sodium may be far more 

 intimate than its ready decomposition by re-crystallization in 

 water would lead one to conjecture. Thus, for instance, urea is 

 only imperfectly separated by nitric acid from a moderately con- 

 centrated aqueous solution, if chloride of sodium be present; 

 urea, moreover, occurs associated with chloride of sodium, even in 

 positions where its presence would not be suspected, as for 



* Arch. f. pathol. Anat. Bd. 3, S, 251. 

 VOL. III. R 



