838 Mr Carpenter on the Differences of the Laws 



to, by which the normal composition of the organic constituents 

 is maintained, the circumstances under Avhich these compounds 

 exist in the living body differ in so many particulars from 

 those of dead matter, that no conclusion could fairly be raised 

 upon the fact of their spontaneous decomposition after death ; 

 since inorganic chemistry affords us numberless examples of 

 such changes occurring under the influence of very slight varia- 

 tions in temperature, electricity, light, &c. Moreover, many 

 proximate principles, when reduced by chemical means to their 

 simplest form, are as permanent as the greater part of the in- 

 organic compounds ; and it is difficult to suppose that they re- 

 tain their vital affinities after being subjected to chemical action. 



Thus starch and gum may be converted into sugar by the operation of va- 

 rious acids ; and sugar at moderate temperatures is as little liable to change 

 as any saline compound. 



£7. It has been said by the physiologist, that the processes 

 of vital chemistry are " not only inexplicable by, but manifestly 

 opposed to, the known action of chemical and physical laws ;" 

 and it is therefore presumed that a distinct set of forces must be 

 in operation, by which these changes are effected ; which forces 

 have received the name of vital affinities. This presumption 

 carries with it a specious probability, and is not easy to be re- 

 futed by positive statements ; we shall examine, however, 

 ■whether the real probability does not support a contrary view. 

 It may be well to repeat that the question we are now arguing 

 relates only to the formation of organic products, such as gum, 

 sugar, albumen, gelatine, &c., which are destined to be further 

 organized — or such as urea, cholesterine, &c. which are to be 

 thrown off from the system, and not to those which, like starch 

 or fat, already present traces of structure, and have therefore 

 partaken of those influences which we consider essentially vital. 



In the first place, then, we may remark that it is rather pre- 

 mature to assert that any such changes in constitution are con- 

 trary to the known laws of chemical affinity ; for no one who 

 has watched the progress of science during the last few years, 

 can hesitate in the belief, that we as yet know but little of those 

 laws, compared with what future discoveries will reveal to us. 

 The same assertion might have been made within a very 

 recent period, with regard to many of those phenomena which. 



