286 BLOOD AND BLOOD EXAMINATION 



V. ALKALINITY 



The estimation of the alkalinity of the blood must be first mentioned. 

 That fresh blood has an alkaline reaction cannot be directly determined by 

 the use of litmus paper on account of the color of the blood, but a particularly 

 sensitive red litmus paper must be moistened with a dilute sodium chlorid 

 solution, then the blood to be tested must be dropped upon it and the paper 

 be rinsed again with a sodium chlorid solution. It is very difficult to deter- 

 mine the degree of alkalinity with any accuracy. In the newer methods the 

 blood to be used is made of a lacquer color, and this is titrated against a 

 normal tartaric acid solution with laemoid paper. For this purpose we usually 

 require somewhat larger quantities of blood, 5 to 8 c.c. ; C. S. Engel has, 

 however, constructed an " alkalimeter " which makes it possible to carry out 

 the test with ^ c.c. of blood. 



How slight is the importance of these investigations, even to-day, is shown 

 by the reports of various authors that even the normal values vary within 

 wide limits; for instance, from 303 (Canard) to 508 (Loewy) mgm. NaOH 

 in 100 c.c. of blood. With such differences in the normal value, it is not 

 surprising that results obtained under pathologic conditions give rise to con- 

 clusions still less definite. Thus, one author found increased alkalinity in 

 certain diseases in which another found decided diminution. 



In the present status of the question, we must be cautious in introducing 

 such an uncertain method of investigation into practice; for, since the result 

 is finally expressed in figures which have a deceptive appearance of exact- 

 ness, it is much more misleading than the most subjective method of exami- 

 nation. 



We are by no means convinced of the biologic importance of the alkaline 

 reaction of the blood. Many authors are inclined to look upon the bactericidal 

 properties of the blood as bearing a certain parallel relation to the alkaline 

 reaction of the blood, but are unable to prove the correctness of this view. 

 Even with such a proof little appears to be gained. For it is self-evident 

 that a definite degree of alkalinity means a relative optimum for bacteria, 

 since the increase of alkalinity at once produces for them unfavorable 

 conditions. 



I must call attention to the fact that Brandenburg may perhaps have 

 opened a way out of these uncertainties by his recent investigations. Bran- 

 denburg demonstrated that we must differentiate between the alkali combined 

 with albumin and that combined with carbonic acid. These elements can 

 be separated from one another since the latter is capable of diffusion, while 

 the alkali combined with albumin is not. Thus it was shown that the 

 diffusible part of alkali represents a very constant value corresponding to 

 about 60 mgm. KaOH— while the non-diffusible part is exposed to the 

 greatest variations. It is now conclusively shown that under pathological 

 conditions even when there is great variation of the total alkalinity from 

 the normal, the amount of diffusible alkali—" the alkali tension "—remains 

 almost unchanged. 



