356 APPENDIX 



Solution for sulphate reduction: 



Tap water 1000.0 c.c. 



K 2 HPO 4 7. 0.5gm. 



Sodium lactate 5.0 gms. 



Asparagin 1.0 gm. 



MgSO 4 1.0 gm. 



A few drops of FeSCU solution. Sterilize in the auto- 

 clav. 



WATER ANALYSIS MEDIA 



Culture media for standard bacteriological water anal- 

 ysis must contain ingredients of a special nature. 



Ingredients. 1. Distilled water in place of tap water. 



2. Infusion of fresh lean meat instead of meat extract. 



3. Witte's peptone (dry, from meat) . 



4. No salt. 



5. Gelatin of the best French brand and as free as pos- 

 sible from acids and other impurities. 



6. Commercial agar of as high a grade of purity as 

 possible. Agar may be purified by washing. 



7. Dextrose, lactose, saccharose, etc., of sugar media, 

 chemically pure. 



8. A 1% aqueous solution of Kahlbaum's azolitmin 

 may be used in place of litmus. 



Sterilization. Sterilize media in the autoclav at 

 120 C. (15 Ibs. pressure) for fifteen minutes. A shorter 

 period than this may result in incomplete sterilization, a 

 longer period will probably result in inversion and cara- 

 melization of the sugars and in lowering the melting-point 

 of the gelatin. Have the sterilizer hot when the medium is 

 inserted so that heating to the point of sterilization will be 

 accomplished as quickly as possible; cool rapidly upon re- 

 moving from the autoclav. 



The Tyndall (intermittent) method may be employed, 

 heating for thirty minutes on three successive days, 



