Sources of Error 



79 



in salt solution were made, and all were allowed to stand in open 

 dishes for 2 hours in order that the volatile antiseptics should evaporate 

 off. The results were compared with serum kept under the same 

 conditions but without the addition of any antiseptic. The following 

 table shows that in nearly all cases the precipitum-forming power was 

 slightly reduced, but in a few completely destroyed. 



The effects of the presence of these substances in fluids to be tested 

 have been given above. 



The results obtained by Graham-Smith and Sanger with carbolic 

 acid and chinosol are considered on page 82, those obtained with lime 

 in Section IX. 



5. The acid or alkaline reaction of the medium. 



Normal blood dilutions possess an alkaline reaction. Tchistovitch 

 (v. 1899) found that precipitation only took place when the reaction 

 was alkaline ; when it was neutral, a slight opalescence was observable ; 

 no reaction took place when the reaction was acid. Linossier and 

 Lemoine (21, iii. '02) found that sulphuric acid in the proportion of 

 •49 : 1000 lessened reaction, that it was reduced to a minimum when 



