Cloudiness in beer is sometimes due to the separating out of albuminous matter from changes in temperature, but usually to the presence of yeast, the fermentation not having been complete. This condition of things is best detected by means of the microscope, which shows the presence of quantities of yeast cells, and, in case other fermentations have set in, of their characteristic bacteria. "Yeast-cloudy" (hefe trubes) beer is considered unhealthy in Germany, and it is considered one of the qualifications of a good beer that it shall be absolutely bright and clear. An extensive investigation of the unhealthfulness of yeast-cloudy beer lately made by Dr. N. P. Simonowsky1 in Pettenkofer's laboratory, who found that such beer had a disturbing effect in both natural and artificial digestion, producing in persons using it obstinate catarrh of the stomach, which persisted for some time. Both Simonowsky and Pettenkofer conclude that the sale of yeast cloudy beer should be prohibited.

The Bavarian chemists at their last meeting at Wurzburg, in August,

1886, adopted the following resolution in relation to yeast-cloudy beer:

Beers which are incompletely fermented for use must he entirely free from yeast; that is, must not contain yeast in a cloudy suspension.

1Zeit. fur das gesammte Brauwesen ?, 9 Jahrg. 1886, No. 7, 8. 9; abstract Bied. Cent., 1887, p. 70