250 INFLUENCE OF FOOD PRESERVATIVES ON HEALTH. 



It must be remembered also in this connection that practically 80 per 

 cent of the preservative administered is recovered in the urine, increas- 

 ing to that extent the total solids thus eliminated. In spite of this, 

 however, there is a marked decrease in the total solids in the urine 

 and a marked increase in the total solids in the feces. 



GENERAL CONCLUSIONS. 



NECESSITY OF MINERAL SUBSTANCES IN THE BLOOD. 



In the consideration of the action of preservatives of a mineral nature, 

 such as borax and boric acid, it must be remembered that the animal 

 as well as the plant possesses a certain mineral hunger. In other 

 words, mineral substances play a double role in animal and plant nutri- 

 tion: First, they may serve as real foods, necessary to the formation 

 and nutrition of the tissues. In the animal economy this is especially 

 true of phosphoric acid and lime. In the second place, they are neces- 

 sary to the functional activity of the various organs of the body, irre- 

 spective of any part they may take in direct nutrition. 



The necessity of saline solutions in the blood is known to every 

 physician and physiologist. If the blood were deprived of all of its 

 saline constituents the circulation would be impeded, restricted, or 

 stopped, and death would result. In cases of collapse in disease saline 

 injections in the blood are often used as a restorative measure. These 

 salts in solution stimulate the heart's action and undoubtedly are active 

 in the osmotic operations of the cells. This is one of the facts which 

 show the intimate relation existing between physical chemistry and 

 physiology. 



Common salt is the most frequent and most abundant of the saline 

 constituents of the blood, but the alkalinity of the blood is not due of 

 course to common salt, which is a neutral substance. The existence 

 of alkaline carbonates or other alkaline salts is necessary to the vital 

 functions. While it is true that the digestion in the stomach takes 

 place in an acid solution, it is likewise true that any excessive acid 

 must be neutralized and enough of alkali added in the small intestine 

 in order that the further digestion of the food may properly take place. 

 That saline bodies other than common salt or the alkaline carbonates 

 may be useful, however, in the performance of the vital functions 

 can not be denied, though it might be difficult to demonstrate their 

 absolute necessit}^. Hence the introduction of saline bodies, which 

 may or may not be of an antiseptic character, may, within certain 

 limits, have a favorable influence upon health and digestion. At the 

 same time it should not be forgotten that all excess of such bodies 

 imposes upon the excretory organs an additional burden, which, while 

 it might not impair their efficiency even for a number of years, might 

 finally produce a condition of exhaustion which would be followed by 



