(43) 



4'^. P' , this is however P-\-p V and therefore known as soon 

 as /; has become known. 



As equation (7) contains 3 unknown quantities three observations 

 will be necessary to determine them. 



When we introduce then the so found values in the other experi- 

 ments and calculating the quantity of precipitate, it appears that the 

 calculated ({uanlities correspond in very satisfactory way wilji those 

 which are observed. 



Let us observe that to avoid superfluous zeros J cc calfserum 

 (/i) is taken = 100. 



While as appears from the experimenis in the case in question 



1l cc calfserum is equivalent to nearly Vs fx* horseseruui 1 : 50, i cc 



horseserum 1 : 50, that is A, obtains a value of 300. 



• . . 0,04 



bo, where m (he lirst experiment —— cc. horse serum was used 



Ö 



0,04 

 A obtains a value of — - X 300 = 4. 



o 



In the experiment, where on 1 cc. calfserum 0,3 cc. horseserum 

 was used, with a value B = 100, A becomes 0,3 X 300 = 90. 



Let us now combine the two tables to one by calculating for the 

 second table how much Veo horseserum is used on 1 calfserum.. 



We .see that the comforuilty between the determined and calcu- 

 lated precipitate [col. HI and I V) is very satisfactory. The average 

 oj- the discrepancy amounts to 1.3. 



This result deserves our attention not only in view of the know- 

 ledge of the precipitin reaction as such, but also from a more 

 general point of view, this reaction belonging to the great group 

 of the toxin-antitoxin reactions. 



Till now, in studying the last, we were obliged to deduce the 

 equilibrium conditions from the toxins, that is to say by determining 

 the toxic action which was left by the gradual saturation of the 

 toxin by increasing quantities of antitoxin, but with the precipitin- 

 reaction the equilibrium conditions may be deduced from the quantity 

 of the formed toxin-antitoxin compound. 



And not only that, but owing to the fact that the compound forms 

 a precipitum, the quantity of this may be fixed in an accurate and 

 direct way by simple measurement, thus without the aid of red blood 

 corpuscles or of injecting-experiments in animals. 



So there is good reason to expect that a further study of the 

 precipitin-reaction will facilitate too the insight in other toxin-anti- 

 toxin reactions. 



