82 



The Precipitins: Methods 



precipitation of the albumen by the dilute acid and were observable 

 within a few minutes. With greater dilutions nothing occurred. It 

 was also found that neutralisation previously with sodium carbonate 

 prevented these cloudings and in some cases even dissolved them after 

 they had been formed. 



One example is given below in detail. 



1—100,000 — — _ _ 



The precise degrees of clouding caused by the various dilutions 

 differ with different acids. 



Some organic acids behaved differently, acetic, oxalic, and tartaric 

 causing little clouding in dilutions of 1 in 10, but marked cloudings in 

 1 in 100 and in 1—1000. 



Details of the action of tartaric acid : — 



Dilutions of Tartaric Acid 

 in salt solution 



1—10 



1—100 



1—1000 



1—10,000 



1—100,000 



Anti-human serum 



Anti-human serum after 

 neutralisation 



1 hour 

 very slight cloud 



medium cloud 



24 hours 

 slight cloud 

 medium cloud 

 marked cloud 

 slight cloud half- 

 way up tube 



1 hour 



24 hours 



The accompanying table shows the chief actions of acid dilutions in 

 salt solution on serum. These effects are more marked when the 

 dilutions are made in distilled water. 



1—10 



1—100 



1—1000 



-10,000 J 

 -100,000 j 



f.SOmins. C 

 |24hrs. D 



cS ?= 



