6. Fill the glass dish with glycerine or metallic mercury to a depth of about 5 cm. [Illustration: FIG. 134.--Botkin's apparatus.] 7. Connect up one U-shaped tube with the hydrogen cylinder (or gas apparatus) by means of rubber tubing. Replace the atmospheric air by hydrogen, as in method IX. 8. Clamp the tubes and disconnect the gas apparatus. 9. Incubate. ~Method XI~ (Novy's Method).-- ~Apparatus Required.~-- Jar for plate cultivations (Fig. 135). _Or_, jar for tube cultivations (Fig. 136). Lubricant for stopper of jar. Rubber tubing. Cylinder of compressed hydrogen. METHOD.-- 1. Prepare cultivations in the usual way. 2. Place these inside the jar. 3. Lubricate the stopper and insert it in the mouth of the jar, with the handle in a line with the two side tubes. 4. Connect up the delivery tube a with the hydrogen gas supply by means of rubber tubing. [Illustration: FIG. 135.--Novy's jar for plate cultivations.] [Illustration: FIG. 136.--Novy's jar for tube cultivations.] 5. Attach a piece of rubber tubing to the exit tube b and collect samples of the issuing gas (over water) and test from time to time. 6. When the air is completely displaced by hydrogen, turn the handle of the stopper at right angles to the line of entry and exit tubes; this seals the orifice of both tubes. 7. Disconnect the gas apparatus and incubate. (E) ~Method XII~ (Bulloch's Method).-- ~Apparatus Required.~-- Bulloch's jar. Pot of resin ointment. Small glass dish 14 cm. diameter by 5 cm. deep. Vessel for tube cultures or metal rack for plate cultures. Pyrogallic acid tablets. Cylinder of compressed hydrogen. Geryk or other air pump. Rubber pressure tubing. 10 c.c. pipette. Glass tubing. Dry granulated caustic soda or compressed tablets each, containing 0.4 grammes sodic hydroxide. Small beaker of water. METHOD.-- 1. Prepare the cultivations in the usual way. 2. Place the glass dish in the centre of the glass slab, and stand the cultivations inside this. 3. Place a sufficient number of pyrogallic acid tablets at one side of the glass dish (i. e., 1 tablet for each 100 cubic centimeters air capacity of the bell jar). Place a small heap of dry granulated soda (or half a dozen tablets of sodic hydroxide) by the side of the pyro tablets. 4. Smear the flange of the bell jar with resin ointment and apply the jar firmly to the glass slab, covering the cultivations--so arranged that the long tube passes with its lower end into the glass dish at a point directly opposite to the pyrogallic acid tablets. Lubricate the two stop-cocks with resin ointment (Fig. 137). 5. Connect up the short tube a with the gas-supply by means of rubber pressure tubing and open both stop-cocks. 6. Connect a long, straight piece of glass tubing to the long tube b by means of a piece of rubber tubing interposing a screw clamp: and collect samples of the issuing gas from time to time and test.