AS WELL AS FOOD. 13 



mous weight of oxygen thus introduced, in the 

 course of a year into the human system ? 



This question may be answered satisfactorily : no 

 part of this oxygen remains in the system ; but it is 

 given out again in the form of a compound of carbon 

 or of hydroQ-en. 



The carbon and hydrogen of certain parts of tlie 

 body have entered into combination with the oxygen 

 introduced through the lungs and through the skin, 

 and have been given out in the forms of carbonic 

 acid gas and the vapour of water. 



At every moment, with every expiration, certain 

 quantities of its elements separate from the animal 

 organism, after having entered into combination, 

 within the body, with the oxygen of the atmosphere. 



If we assume, with Lavoisier and Seguin, in 

 order to obtain a foundation for our calculation, 

 that an adult man receives into his system daily 

 32^ oz. (46,037 cubic inches =15,661 grains, French 

 weight) of oxygen, and that the weight of the whole 

 mass of his blood, of which 80 per cent, is water, is 

 24 lbs.; it then appears, from the known composi- 

 tion of the blood, that, in order to convert the 

 whole of its carbon and hvdroo'en into carbonic acid 

 and water, 64,103 grains of oxygen are required. 

 This quantity will be taken into the system of an 

 adult in four days five hours. (2) 



Whether this oxygen enters into combination 

 with the elements of the blood, or with other parts 

 of the bodv containino- carbon and livdroffen, in 



