BY DR. BURDON-SANDERSON. 201 



until the filtrate is colorless. The pink fibrin thus obtained is 

 then finally washed on the filter with boiling alcohol, dried 

 first in the air-bath, then over sulphuric acid, and finally 

 weighed. 



3. A third portion of blood is received in a similar apparatus, 

 defibrinated, and the defibrinated blood strained through a 

 calico filter and weighed. The filtrate is then mixed in a tall 

 jar, with ten volumes of a solution of salt, prepared \)y adding 

 nine volumes of water to one of saturated solution. After a 

 day, the corpuscles having subsided, the liquid is decanted 

 oft', and replaced by a second similar quantity of saline solu- 

 tion. Again the corpuscles are allowed to subside, and the 

 liquor removed by decantation. The deposit is then washed 

 with water into a porcelain capsule, evaporated on the water- 

 bath, dried, pulverized with alcohol, and then proceeded with 

 for the separation of the albuminous compounds from the 

 soluble constituents, as in the first quantity. The weight of 

 the insoluble residue (c), minus the weight of its salts, corre- 

 sponds to that of the albumin and haemoglobin of the whole 

 blood. 



4. The fourth quantity is allowed to coagulate in a capsule. 

 The serum is then poured off, and the albumin contained in 

 a weighed quantity determined by the method already de- 

 scribed. 



The results stand as follows : From 3, we learn the propor- 

 tion in a known weight of blood, of albumin and haemoglobin 

 contained in the corpuscles; from 1, the corresponding pro- 

 portion of albumin and haemoglobin contained in the corpus- 

 cles and plasma together; and herce, by deducting the former 

 from the latter, the proportion of albumin in the plasma. 

 From 4, the proportion of albumin contained in the serum is 

 known, and thereby that of the serum in the blood. The 

 weight of the plasma is equal to the weight of the fibrin (2), 

 plus that of the serum. Finally, by deducting the weight of 

 the plasma from that of the blood, we have that of the corpus- 

 cles in the moist. 



24. Quantitative Determination of the Haemoglobin 

 contained in Blood. It is often of great importance to be 

 able to determine the proportion of haemoglobin in a small 

 quantity of blood ; such, for example, as may be obtained by 

 cupping. This is accomplished by making a solution of a 

 measured or weighed quantity of blood in water, and then 

 ascertaining, witli the aid of the spectroscope, what degree of 

 dilution is necessary in order to bring it to such a strength 

 that only the red rays are transmitted (see 18). The point 

 of dilution at which the green is entirely extinguished, has 

 been found by Preyer to be so constant, that it may be used 

 as a basis for quantitative determinations. 



