214 BLOOD. 



enclosed in the clot, is still adhering to the blood-corpuscles, and 

 must accordingly be deducted. The worst deficiency in all blood- 

 analyses however is, that the errors are not constant, even when the 

 same method is employed ; that is to say, the acknowledged error 

 in every analytical method is of variable magnitude, so that even 

 the comparative blood-analyses made according to one and the 

 same method a procedure on which the French chemists lay 

 such stress have only a very subordinate value for physiology 

 and pathology, and the conclusions drawn from them can only be 

 received with the most extreme caution. We must confess with 

 sorrow, that even at the present day the analysis of the blood must 

 be ranked amongst the most uncertain and untrustworthy investi- 

 gations in the whole department of analytical chemistry. Hence, 

 the attempt which has been recently made (by Hinterberger under 

 the superintendence of v. Gorup-Besanez*) to prove experimentally 

 the comparative certainty of the different methods of analysing the 

 blood, is the more praiseworthy ; it is only in this way that we shall 

 attain to what at present seems in some measure impossible. We 

 ought not, however, to expect that chemistry at its beginning 

 should equally distribute its full light over a field on which 

 scarcely a glimmer of twilight has fallen during preceding centu- 

 ries of investigation. 



Most of the experimenters who have made large series of blood- 

 analyses, namely, Andral and Gavarret,f Becquerel and Rodier,{ 

 and Popp, have scarcely at all deviated from the method by which 

 Prevost and Dumas || determined the dry blood-corpuscles. This 

 method consisted, essentially, in separately weighing the serum and 

 the clot, after the perfect contraction of the latter, in order to 

 determine the ratio in which they stood to each other ; the solid 

 residue of the serum was then determined, as also was that of the 

 clot ; on deducting the fibrin, which had been otherwise determined, 

 from the solid residue of the clot, we obtain the number which 

 expresses the sum of the dry blood- corpuscles and of the solid 

 residue of the serum still enclosed in the clot. It is in the 

 accurate determination of the amount of this serum that our most 

 able experimentalists have broken down. Since the amount of 



* Arch, f, phys. Heilk. Bd. 8, S. 603618. 

 t Ann. de Chim. et de Phys. T. 55, p. 227. 

 $ Gaz. ineU de Paris, 1844. No. 47, p. 751. 



Untersuchungen uber die Beschaffenheit des menschl. Blutes in 

 verschiedenen Krankheiten. Leipzig, 1845, S. 68. 



|| Ann. de Chim. et de Phys. T. 23, pp. 5675. * 



