CULTURE MEDIA FOR CULTIVATION OF MICROORGANISMS 



807 



(7) Sterilize 30 minutes at 100°C. on 

 each of 3 successive daj^s. 

 (g) Heinemann gave the following 

 method of preparation: 



(1) Mix 100.0 cc. of HCl (sp. gr. 1.10 

 Beaume's scale at 60°F.) with 

 100.0 cc. of sodium silicate (sp. gr. 

 1.09° Beaume's scale at 60°F.). 



(2) Place (1) in colloidal sacs and 

 dialyze in running water for 

 12 hours. 



(3) Dissolve 0.4 g. (NH4)2S04, 0.05 g. 

 MgS04, 0.1 g. KH.,P04, 0.9 g. 

 NaaCOs and 0.01 g. CaCh in the 

 smallest amount distilled water 

 possible. 



(4) Heat both (3) and (2) to boiling 

 and cool rapidly without stirring. 



(5) Mix the two solutions. 



(6) Tube or pour into Petri dishes. 

 (Slant the tubes.) 



(7) Sterilize in the autoclave at 110°C. 

 References: Sleskin (1891 p. 210), Burri 



and Stutzer (1895 p. 723), Fremlin (1903 

 p. 271), Smith (1905 p. 198), Johnson 

 (1912 p. 218), Abbott (1921 p. 604), Harvey 

 (1921-22 p. 106), Heinemann (1922 p. 38). 



2472. Omelianski's Ammonium Sulphate 

 Silicate Jelly 



Constituents: 



1 Water 1000.0 cc. 



2. HCI 100.0 cc. 



3. Waterglass 100.0 cc. 



4. Potassium phosphate 1.0 g. 



5. MgS04 0.5 g. 



6. (NH4)2S04 3.0 g. 



7. FeS04 



8. NaCl 



9. MgCOa 

 Preparation : 



(1) Mix equal volumes of waterglass 

 (sp. gr. 1.05-1.06) and HCl (sp. gr. 

 1.10). 



(2) Dialyze using parchment until all 

 traces of chlorine have been removed. 

 There are 2 parts SiOs in a 100 parts 

 of this solution. The specific gravity 

 at 16°C. measured with a pyknometic 

 is 1.0121. This solution may be 

 sterilized at 115-120°C. 



(3) Dissolve 4, 5 and 6 in 1000.0 cc. dis- 

 tilled water. 



(4) Prepare a 2.0% FeS04 solution. 



(5) Prepare a saturated salt solution. 



(6) Prepare milk of magnesia— that is a 

 suspension of MgCOs in water. 



(7) To 50.0 cc. of (2) add 2.5 cc. of (3) 

 and 1.0 cc. of (4). 



(8) Distribute into plates or tubes. 



(9) Add all the way from a platinum loop 

 to a small drop of (5) to each tube or 

 plate and (6) may be added until the 

 gel becomes milky. (Soda, about 

 0.1% may be used instead of MgCOs.) 



Sterilization: Not specified. 



Use: Isolation of nitrifying organisms. 

 The plates or tubes may be inoculated 

 while the mixture is still a liquid, or after 

 solidification takes place which requires 

 about an hour. 



Variants: Stevens and Temple (Percival) 

 prepared a similar medium as follows: 



(1) Take 3 to 4.0 cc. of a solution of so- 

 dium silicate (waterglass) and place 

 in a porcelain dish. 



(2) Add 5.0 to 10.0 cc. of a concentrated 

 HCl to precipitate the silicic acid. 



(3) Evaporate to dryness. 



(4) Moisten again with HCl and evap- 

 orate to dryness again. 



(5) Wash and transfer to a Swedish filter 

 paper, the weight of whose ash is 

 known. 



(6) Wash the precipitate until it gives 

 no cloudiness when treated with 

 silver nitrate solution. 



(7) Burn the filter with the precipitate 

 on it in a weighed porcelain crucible 

 and heat to redness. 



(8) Allow to cool and weigh the silicic 

 anhydride (Si02). 



(9) Calculate the amount of silicic an- 

 hydride in 1.0 cc. of the original 

 solution. 



(10) Dilute the amount of waterglass 

 which is to be used for the prepara- 

 tion of the jelly until the solution 

 contains 4 to 5.0%, silicic anhydride. 



(11) Prepare a hydrochloric acid of such 

 strength that 1.0 cc. just neutralizes 

 1.0 cc. of (10) using methyl orange 

 as an indicator. 



(12) Take 104.0 cc. of (11) and add 

 100.0 cc. of (10). 



(13) Distribute in tubes or flasks and 

 sterilize at 120° for 15 minutes or at 



