APPENDIX TO CHAPTER III 



Specifications for Bacteriological Grade 

 Agar, Gelatin, and Peptones 



BACTERIOLOGICAL GRADE AGAR^ 

 Suggested Specifications 



Definition. Agar is any phycocoUoid derived from Rhodophyceae which meets the 

 requirements given below for gelation temperature and gel melting temperature. 

 Bacteriological grade agar meets all the stated requirements. 



Forms. Bacteriological grade agar shall be in the form of shreds, flakes, strips, 

 sheets, or granules. 



Table 4. Requirements 



Determination 



Total solids 



Solubility, cold, % 



Solubility, hot, % 



Gelation temperature, °C 



Gel melting temperature, °C 



Rate of dissolution, min 



Sol turbidity, ppm 



Threshold gel concentration, % 



Protein nitrogen, % 



Reducing substances as galactose, % 



Chlorides as NaCl, % 



Viable spores, per g 



Debris count, per g 



Limits 



Analytical Methods 



Total solids. Dry accurately weighed duplicate samples of 0.6-1.0 g for 5 hr at 

 105°C. Cover, cool to ambient temperature in desiccator, and weigh. Caution: 



^ These specifications were prepared by Mr. H. H. Selby of the American Agar and 

 Chemical Co., San Diego 12, California. They were originally presented to the Society 

 of American Bacteriologists Committee on Bacteriological Technic at the 53d general 

 meeting, San Francisco, California, 1953. 



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