CONTENTS V 



Further Observations on the "Color Standards" for the Colorunetric Deter- 

 mination of H-Ion Concentration. L. S. Medalia 589 



The Cause of Explosion in Chocolate Candies. John Weinzirl 599 



Microorganisms Concerned in the Oxidation of Sulfur in the Soil. IV. A 

 Solid Medium for the Isolation and Cultivation of Thiobacillus ihio- 

 oxidans. Selman A. Waksman C05 



Microorganisms Concerned in the Oxidation of Sulfur in the Soil. V. Bac- 

 teria Oxidizing Sulfur under Acid and Alkaline Conditions. Selman A. 

 Waksman 609 



