180 DETERMINATION OF FIBRIN. [BOOK I. 



The insoluble matters together with the small filter previously 

 referred to, are now dried in the hot-air oven and then ignited 

 at a red heat ; when the whole of the carbon has been burned 

 away the crucible is cooled and the solution of the soluble salts 

 added to it; the contents are first evaporated to dryness in the 

 water and air ovens and then ignited at a barely perceptible red 

 heat; the crucible is then cooled and weighed, and thus the total 

 amount of ash found. Or, by weighing in separate crucibles the 

 aqueous solution and the ignited insoluble residue, the amount of 

 soluble and insoluble constituents of the ash is ascertained *. 



Determination of the amount of Fibrin yielded by the Blood. 



If it be desired to determine the amount of fibrin which will 

 separate from the blood, the best method is the following : 



Hoppe- A beaker, of a capacity between 100 and 150 c.c., is 



Seyier's fitted with a caoutchouc cap, provided with a single opening 



method. i n ^he centre through which is thrust a rod of vulcanite, 



somewhat spatula-shaped at its lower end (Fig. 35). The weight of 



FIG. 35. HOPPE-SEYLEP.'S APPABATUS FOB SEPARATING FIBRIN FROM THE BLOOD. 



1 The most valuable determinations of the salts of the serum have been made by 

 the method of direct precipitation. It has been shewn that sulphuric and phosphoric 

 acids, calcium, and magnesium may be precipitated from serum, as from aqueou 

 solutions ; the precipitates are separated by subjecting the liquid to rapid rotation in th 

 centrifugal machine; with the aid of the latter they may be efficiently and rapidly 

 subjected to the process of 'washing by decantation ', and then treated according tc 

 the ordinary methods. The reader who wishes to pursue researches in this directic 

 should consult the account given of these methods by Pribram and Gerlach (see p. 6C 



