82 ARTERIAL AND VENOUS BLOOD. 



at a temperature of no C. The loss of weight represents the amount of water 

 that was present. The dry residue is determined by subtracting the weight of 

 the crucible. For clinical purposes Stintzing weighs a few drops of blood in a 

 Hight, covered glass dish. This he dries for six hours at a temperature of 65 C. 

 -raaid weighs the residue. The amount of water was found to be in men 78.3, 

 Tin women 79.8. The dry residue corresponds approximately with the amount of 

 rproteids contained in the blood and it declines in the presence of anemia. 



Estimation of the Fibrin. A measured volume of blood is whipped with a rod. 

 After complete separation, all of the fibrin is collected upon a satin filter and 

 washed with water; then placed in a dish and again washed with water, alcohol 

 and ether; next dried in a drying chamber at a temperature of 110 C., and 

 finally weighed. Kossler and Pfeiffer estimate the amount of nitrogen in the 

 serum and in the plasma according to the method of Kjeldahl; the difference 

 represents the amount of nitrogen in the fibrin. The fibrin in 100 cu. cm. of plasma 

 contains 39 mg. of nitrogen (from 30.8 to 45). The fibrin is increased in cases of 

 pneumonia, acute articular rheumatism, erysipelas, scarlet fever, peritonitis (to 

 between 80 and 152 mg.). 



Estimation of the Fats (Ethereal Extract} in the Serum or the Total Blood. 

 About 15 grams of defibrinated blood or serum are dried in a dish at first over 

 a water-bath, then in a drying chamber at a temperature of 120 O., rubbed up, 

 and placed in a flask with ether, which is repeatedly renewed. 



The method just described is followed in preparing an alcoholic extract from 

 the total blood or the serum. 



Estimation of the Inorganic Salts in the Total Blood or Serum. About 25 grams 

 are dried in a weighed platinum crucible and then reduced to ash over a free 

 flame at red heat. The amount of ash is determined by weighing. If this ash 

 be repeatedly extracted with hot water, and the latter be entirely evaporated in 

 a weighed dish, the weight of the salts soluble in water will be obtained. 



Estimation of the Total Proteids in Blood or Serum. E. Salkowski precipitates 

 all albuminates by means of sodium chlorid and acetic acid. For this purpose 

 he places 20 grams of pulverized sodium chlorid and 50 cu. cm. of blood in a dry 

 flask and adds 100 cu. cm. of a mixture of 7 volumes of concentrated solution 

 of sodium chlorid and i volume of acetic acid, agitating for 20 minutes and 

 filtering- The filter is dried and weighed. V. Jaksch takes i gram of blood from 

 a cupping glass, estimates the amount of nitrogen contained by the method of 

 Kjeldahl, and multiplies the result obtained by 6.25. 



Estimation of the Proteids of the Blood-corpuscles. If the proteids contained 

 in one part by weight of the total blood and also of the serum have been deter- 

 mined, and if the amount obtained for the serum be deducted from that obtained 

 for the total blood in the proportion in which red blood-corpuscles and serum are 

 present in the total blood, the result will represent the proteids of the blood-corpus- 

 cles, although only approximately. 



Estimation of the Red Blood-corpuscles by Weight. Defibrinated blood is mixed 

 with thrice its volume of a concentrated solution of sodium sulphate and filtered. 

 The blood-corpuscles remaining upon the filter are coagulated by immersing the 

 filter in boiling concentrated solution of sodium sulphate. Then the filter can be 

 washed out with distilled water, after which it is dried and weighed. The increase 

 in the weight of the previously weighed filter is due to the presence of the blood- 

 corpuscles. 



ARTERIAL AND VENOUS BLOOD. 



Arterial blood contains in solution all those materials that are neces- 

 sary for the nutrition of the tissues, many that are to be employed in 

 secretion and in addition the larger amount of oxygen. Venous blood 

 need contain less of these matters, while the waste materials of the 

 tissues, the products of retrogressive metamorphosis, will be present in 

 greater amount, including a larger quantity of carbon dioxid. As, 

 however, the interchange through the blood takes place rapidly, no 

 great difference in many of these substances can be looked for at a 

 given moment. In many respects analysis fails to furnish conclusive 

 evidence. A little consideration, further, will show that the blood from 



