TRANSFORMATIONS OF ORGANIC SUBSTANCES. 73 



of decomposition generally, the oxygen of the in- 

 spired air cannot combine directly with the carbon 

 of compounds of that element contained in the 

 blood ; the hydrogen only can combine with the 

 oxygen of the air, or undergo a higher degree of 

 oxidation. Oxygen is absorbed without uniting with 

 carbon ; and carbonic acid is disengaged, the car- 

 bon and oxygen of which must be derived from 

 matters previously existing in the blood.* 



All superabundant nitrogen is eliminated from the 

 body, as a liquid excrement, through the urinary 

 passages ; all solid substances, incapable of further 

 transformation, pass out by the intestinal canal, and 

 all gaseous matter by the lungs. 



We should not permit ourselves to be withheld 

 by the idea of a vital principle, from considering in 

 a chemical point of view the process of the transfor- 

 mation of the food, and its assimilation by the 

 various organs. This is the more necessary, as the 

 views, hitherto held, have produced no results, and 

 are quite incapable of useful application. 



Is it truly vitality, w^hich generates sugar in the 

 germ for the nutrition of young plants, or which 

 gives to the stomach the power to dissolve, and to 

 prepare for assimilation, all the matter introduced 

 into it ? A decoction of malt possesses as little 

 power to reproduce itself, as the stomach of a dead 

 calf; both are, unquestionably, destitute of life. 



* The examination of the air expired by consumptive persons, as 

 well as of their blood, would doubtless throw much light on the nature 

 of phthisis pulmonalis. Considered in a chemical point of view, the 

 decojuposition of the blood, as it takes place in the lungs, is a true 

 process of putrefaction. (See Part II.) The lungs are also the seat 

 of the transformation of the various substances contained in the blood. 

 It certainly well merits consideration, that the most approved reme- 

 dies for counteracting or stopping the progress of this frightful malady 

 are precisely those which are found most efficacious in retarding putre- 

 faction. Thus, it is well known, that much relief is afforded by a 

 residence in works in which empyreumatic oils are manufactured by- 

 dry distillation, such as manufactories for the preparation of gas or sal- 

 ammoniac. For the same reason, the respiration of wood vinegar 

 (pyroligneous acid), of chlorine, and certain of the acids, has been, 

 recognised as a means of alleviating the disease. — L. 



7 



