284 INDUCTION. 



spirituous liquors.) 4th. In any state of the body in which pecuhar 

 gases are fonneJ within it, these wll rapidly exhale through all parts 

 of the body; and hence the rapidity with which, in certain states of 

 disease, the suiTOunding atmosphere becomes tainted. 5th. The putre- 

 faction of the interior parts of a carcass will proceed as rapidly as that of 

 the exterior, from the ready passage outwards of the gaseous products. 

 .6th. The exchange of oxygen and carbonic acid in the lungs is not pre- 

 vented but rather promoted, by the intei-\'ention of the membrane of 

 the lungs and the coats of the blood vessels between the blood and the 

 air. It is necessary, however, that there should be a substance in the 

 blood with which the oxygen of the air may immediately combine, 

 otherwise, instead of passing into the blood, it would permeate the 

 whole organism ; and it is necessary that the carbonic acid, as it is 

 formed in the capillaries, should also find a substance in the blood with 

 which it can combine ; other^vise it would leave the body at all points, 

 instead of being discharged through the lungs. 



§ 5. The foUowmg is a deduction which confirms, by explaining, the 

 old but not undisputed empirical generalization that soda powders 

 weaken the hirman system. These powders, consisting of a mixture 

 of tartaric acid with bicarbonate of soda, from vvhich the carbonic acid 

 is set free, must pass into the stomach as tartrate of soda. Now, 

 neuti-al tartrates, citi-ates, and acetates of the alkalis are found, in their 

 passage through the system, to be changed into carbonates ; and to 

 convert a tartrate into a carbonate requires an additional quantity of 

 oxygen, the abstraction of which must lessen the oxygen destined for 

 assimilation with the blood, and to the quantity of which the vigorous 

 action of the human system is proportional. 



The instances of new theories agreeing with and explaining old em- 

 piricisms, are innumerable. All the just remarks made by experienced 

 persons on human character and conduct, are so many special laws, 

 which the general laws of the human mind explain and resolve. The 

 empirical generalizations on which the operations of the arts have 

 usually been founded, are continually justified and confiiTned on the 

 one hand, or rectified and improved on the other; by the discovery of 

 the simpler scientific laws on which the efficacy of those operations 

 depends. The effects of the rotation of crops, of the various manures, 

 and the other processes of improved agriculture, have been, for the 

 first time, resolved in our own day into known laws of chemical and 

 organic action, by DaN^y and Liebig. The processes of the healing 

 art are even now mostly empirical ; their efficacy is concluded, in each 

 instance, from a special and most precarious experimental generaliza- 

 tion : but as science advances, in discovering the simple laws of chem- 

 istry and physiology, progress is made in ascertaining the intcnnediate 

 links in the series of phenomena, and the more general laws on which 

 they depend : and thus, while the old processes are either exploded, 

 or their efficacy, in so far as real, explained, improved processes, 

 founded on the knowledge of proximate causes, are continually sug- 

 gested and brought into use,* Many even of the tiniths of geometry 



* It was an old generalization in surgery, that tight bandaging had a tendency to prevent 

 or dissipate local inflammations. This sequence being, in the progress of physiological 

 knowledge, resolved into more general laws, led to. the important surgical invention 

 recently made by Dr. Atnott, the treatment of local inflammation and tumors by means of 



