502 Bulletin 167 



One was treated with a few drops of Millon's reagent, 1 another 

 with two or three drops of dilute solution of ferric chlorid, and 

 the third with a few drops of strong- bromine water. 2 The results 

 were negative. 



The reaction for phenol is sometimes obscured by the pres- 

 ence of traces of indol. To eliminate this source of error 200 cc. 

 cultures were distilled with 50 cc. of concentrated hydrochloric 

 acid. The 70 cc. of distillate obtained was rendered alkaline with 

 potassium hydroxid and again distilled. Indol should come over 

 in the distillate while phenol remains in the residue. The residue 

 was cooled, saturated with carbon dioxid and distilled. This 

 final distillate was tested as before for phenol with negative 

 results. 



Hydrogen sulphid production. — This was determined in 

 bouillon tubes in the upper portion of which were suspended 

 strips of filter paper moistened with lead acetate solution. The 

 moisture was renewed with distilled water as was deemed neces- 

 sary. No signs of hydrogen sulphid appeared until the fourth 

 day, when traces of the black sulphid of lead appeared upon the 

 moist paper. The reaction became more pronounced a? the age 

 of the culture increased. 



Toleration of acids. — Ordinary beef bouillon having a reac- 

 tion of o Fuller's scale was used in this work. Hydrochloric 

 and acetic acids were tested. Sufficient normal acid was added 

 to 100 cc. portions of bouillon to secure a reaction of +5, +10 

 and so on for every 5 degrees Fuller's scale up to +50. Good 

 growth resulted within 24 hours in tubes containing hydrochloric 

 acid up to and including +20. Growth was observed in tubes 

 having a reaction of -j-25 at the end of 2 days, and in 2 of the 



1 Prepared by heating one part of mercury with two parts of nitric 

 acid, specific gravity 1.4, until the mercury was completely dissolved, 

 and then diluting the solution obtained with twice its volume of dis- 

 tilled water. Salkowski & Orndorff. Laboratory Manual of Physiologi- 

 cal and Pathological Chemistry, p. 251 (1904). 



2 Chester, F. D. Manual of Determinative Bacteriology, p. ?..) 

 (1901). Salkowski & Orndorff, pp. 106 and 1G1. 



