128 THE BLOOD. 



human blood, indicating certain proportions of albumen, 

 lactate of soda, muriate of soda, etc. ; lie was followed by 

 Marcet in 1811, by whom his observations were confirmed. 

 In 1823, Provost and Dumas published their elaborate re- 

 searches into the composition of the blood, which seemed to 

 give an impulse to investigations in this direction, and were 

 soon followed by the analyses of Andral and Gavarret, Leh- 

 mann, Simon, Becquerel and Eodier, Denis, and a host of 

 others, whose labors have made us comprehend some of the 

 most important laws which regulate the general processes of 

 nutrition. 



Notwithstanding the immense amount of labor bestowed 

 by the most eminent chemists of the day upon the quantita- 

 tive analysis of the blood, and the great physiological interest 

 attaching to every advance in our knowledge in this direction, 

 the difficulties in the way are so great, that even now there 

 are no analyses which give the exact quantities of each of its 

 inorganic constituents. This is owing to the great difficulty 

 in the analysis of any fluid in which inorganic and or- 

 ganic principles are so closely united ; for there is no more 

 delicate problem in analytical chemistry than the determina- 

 tion of the presence and quantities of inorganic substances 

 united with organic matter. Of the animal fluids which are 

 easily obtained, the blood, from the large proportion of differ- 

 ent organic principles which enter into its composition, presents 

 the greatest difficulties to the analytical chemist. Another 

 difficulty presents itself in the necessity of & proximate, and not 

 an ultimate analysis. It is not sufficient to give the amount 

 of certain chemical elements which the blood contains ; we 

 must ascertain the amount of these elements in the state of 

 union with each other to form proximate principles. 



Analyses have shown that the constituents of the blood 

 may be divided into : 



1. Inorganic Constituents. These exist in a state of inti- 

 mate and molecular union with the organic-nitrogenized ele- 



