zymoscope

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun An instrument used to determine fermentation efficiency by measurement of carbon dioxide produced.

from The Century Dictionary.

• noun An instrument, contrived by Zenneck, for testing the fermenting power of yeast, by bringing it in contact with sugar-water and observing the quantity of carbonic anhydrid evolved.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Physiol. Chem.) An apparatus for determining the fermenting power of yeast by measuring the amount of carbonic acid evolved from a given quantity of sugar.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun a zymometer