McIntosh and Filde's anaerobic jar

The jar, about 20″×12.5″ is made up of a metal. Its parts are as follows:

1. The body made up of metal (airtight)
2. The lid, also metal can be placed in an airtight fashion
3. A screw going through a curved metal strip to secure and hold the lid in place
4. A thermometer to measuring the internal temperature
5. A pressure gauge to measuring the internal pressure (or a side tube is attached to a manometer)
6. Another side tube for evacuation and introduction of gases (to a gas cylinder or a vacuum pump)
7. A wire cage hanging from the lid to hold a catalyst that makes hydrogen react to oxygen without the need of any ignition source

• First:

1. The culture: The culture media are placed inside the jar, stacked up one on the other, and
2. Indicator system: Pseudomonas aeruginosa, inoculated on to a nutrient agar plate is kept inside the jar along with the other plates. This bacteria need oxygen to grow (aerobic). A growth free culture plate at the end of the process indicates a successful anaerobiosis. However, P. aeruginosa possesses a denitrification pathway. If nitrate is present in the media, P. aeruginosa may still grow under anaerobic conditions.

• Second: ⁶/₇^ths of the air inside is pumped out and replaced with either unmixed Hydrogen or as a 10%CO₂+90%H₂ mixture. The catalyst (Palladium) acts and the oxygen is used up in forming water with the hydrogen. The manometer registers this as a fall in the internal pressure of the jar.

• Third: Hydrogen is pumped in to fill up the jar so that the pressure inside equals atmospheric pressure. The jar is now incubated at desired temperature settings.