PREFACE. 





THE Royal Academy of Sciences at Stock* 

 holm elects its President every half year from 

 among its Members ; and it is required, by the 

 statutes of the Academy, that whoever has filled 

 that office should, upon leaving it, read an Essay 9 

 or deliver a Speech, on some literary or scientific 

 subject of his own choice. This regulation gave 

 rise to the present Treatise, the Author of 

 which has occupied himself very much with in- 

 vestigations in Animal Chemistry, and> several 

 years ago, published a Work, in two volumes, 

 on this new branch of Science. In the year 

 1810, when he gave up his f residency in 



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