136 



THE BLOOD 



Chlorine 0.898 



Sulphuric acid 0.031 



Phosphoric acid o . 695 



Potassium i . 586 



Sodium 0.241 



Phosphate of lime o . 048 



Phosphate of magnesium 0-031 



Oxygen 0.206 



Blood Plasma 486 . 89 



Water 439 . 02 



Substances not vaporizing at 1 20 47 . 96 



Fibrin 



Protein, etc 



Inorganic constituents 



Chlorine 



Sulphuric 



Phosphoric acid 



Potassium 



Sodium 



Phosphate of lime 



Phosphate of magnesium .... 

 Oxygen 



Specific Gravity = 1.0599. 



Chloride of potassium . . . 

 Sulphate of potassium . . . 

 Phosphate of potassium. . 

 Phosphate of sodium .... 



Soda 



Phosphate of lime 



Phosphate of magnesium. 



Total. . 



1.887 

 0.068 



1 . 202 

 0.325 

 0-175 

 0.048 



o . 03 1 



Total. 



4.142 



The Composition of Plasma. The plasma is the liquid part of the 

 blood in which the corpuscles float. It differs from the serum only in that 

 the fibrin factors have been removed during the process of clotting. To 

 all intents and purposes the chemistry of the plasma and serum are iden- 

 tical. Plasma may be freed from the corpuscles by the centrifugal 

 machine in the interval before clotting forms. However, it is customary 

 to delay clotting by means enumerated below. 



Cooled Plasma. If blood is drawn directly into a chilled vessel and 

 kept at a temperature of about o C., or only two or three degrees higher, the 

 corpuscles will settle out, leaving a clear supernatant plasma. This plasma 

 will clot promptly on raising the temperature. This method yields a 

 pure plasma for isolation of fibrinogen and for quantitative analysis. 



Salted Plasma. Blood will not clot if it is mixed with sodium sulphate 

 or magnesium sulphate in adequate proportion, one part to twelve parts 

 of blood of the former, and one part to six parts of blood of the latter. 

 Salted plasma obtained by this method will coagulate on dilution. 



Oxalated Plasma. In experimental work it is customary to prevent 

 blood clotting by receiving it into an oxalate solution or over a powder of 

 an oxalate salt. It is necessary that the blood contain at least one tenth 

 per cent, of oxalate. The oxalate removes the soluble calcium salts before 

 the prothrombin is converted into thrombin. Oxalated plasma will not 



