1 66 APPENDIX. 



opalescence is produced, but with an increased 

 globulin content, such as is seen in secondary 

 syphilis, the mixture becomes cloudy and shows 

 a distinct flocculent precipitate in about half an 

 hour. With butyric acid the appearance of the 

 precipitate is quite characteristic; with other acids 

 much less differentation is obtained. 



The technique of the butyric acid test is as 

 follows : 



For Serum To i cc. serum add 4 cc. half-satu- 

 rated solution ammonium sulphate. After two 

 hours, centrifuge at high speed for 15 minutes. 

 Pour off the supernatant fluid, and dissolve the 

 precipitate in 10 cc. physiological salt solution. 

 To 0.5 cc. of this solution add 0.5 cc. of a 10% 

 solution of butyric acid in salt solution. A floccu- 

 lent precipitate within two hours constitutes a 

 positive test. Readings made after that time may 

 lead to erroneous conclusions, as even non-syphili- 

 tic sera may give a slight precipitation under these 

 circumstances. 



For Cerebro > spinal Fluid. The preliminary pre- 

 cipitation with ammonium sulphate is omitted. 

 To o.i cc. of the fluid add 0.5 cc. of the 10% solu- 

 tion of butyric acid in salt solution. Heat to boil- 

 ing, and add o.i cc. normal NaOH. Observe the 

 tubss at the end of ten to twenty minutes. A posi- 

 tive reaction is indicated by the appearance of a 

 coarsely granular or flocculent precipitate. With 

 a negative reaction there is merely a uniform cloud- 

 ing, but no such precipitate. 



