ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 59 
‘Use of Gelatinous Silica for the Clarification of Beer.’ P.Drprax. (‘ Ann. Brass. 
et. Dist.’ 1912, 15, 410. Abst. ‘J. Inst. Brewing,’ 1913, 19, 52.) 
* On the Flocculation or “‘ Break ”’ of Worts and Beers and its Significance in Brewing 
Practice.’ Horacz T. Brown. (‘J. Inst. Brewing,’ 1913, 19, 84.) 
The persistent turbidity produced on cooling a hopped malt wort is occasioned 
by a suspension of particles of a tannin-protein compound soluble in hot wort, in- 
soluble in cold. Most of the particles are formed during cooling between the limits 
of 49° C. and 27° C. I£ the wort is strongly agitated when cooling between these 
limits, flocculation takes place, otherwise flocculation is rendered difficult owing to 
the protective influence of the dextrins of the wort. A suspension of the tannin- 
protein compound is injurious to the propagation and fermentative power of yeast, 
and adversely affects the flavour of the resulting beer owing to adsorption of hop 
resin on the surface of the suspended particles. A technical means of inducing 
flocculation during cooling of the wort is indicated. 
* Practical Observations and Studies of Albumin Turbidities in Beer caused by Tin 
and Iron.’ G. L. Goos. (‘ Highth Internat. Cong. Appl. Chemistry,’ 1912. 
Abst. ‘J. Inst. Browing,’ 1913, 19, 147.) 
‘Head on Beer.’ A. Fernpacu. (‘ Ann. Brass. et Dist.’ 1918, 16, 145. Abst. ‘J. 
Inst. Brewing,’ 1913, 19, 400.) 
The relation of the colloids of beer to the formation, nature, and retention of 
‘head ’ is discussed. 
* Electrical Dialysis of Enzymes: Application of the Principle to the Purification of 
Malt Diastase.’ M. Lissonnz and M. Vuxquin. (‘ Journ, de Physiol. et Pathol.’ 
1913, 15, 24. Abst. ‘J. Inst. Brewing,’ 1914, 20, 64.) 
‘Removal of Oil from Condenser Water by Electrolysis.’ H. WINKELMANN. 
(‘Zeitschr. ges. Brauw. 1913, 36, 664. Abst. ‘J. Inst. Brewing,’ 1914, 20, 78.) 
‘ Colloids as Vehicles of Undesirable Flavour in Beer.’ F:Emsntanprr. (‘ Wochenschr. 
Brau.’ 1913, 30, 387. Abst. ‘J. Inst. Brewing,’ 1914, 20, 80.) 
‘Plant Colloids, II].—Processes of Solution and Removal of the Ash of Starch.’ 
M. Samec and F. von Honrrr. (‘ Koll. Chem. Beihefte,’ 1913, 5, 141. Abst. 
‘J. Inst. Brewing,’ 1914, 20, 124.) 
“Concentration of Hydrogen Ions in Beer, and its Relation to the Brewing Process.’ 
F. Emsntanper. (‘ Zeitschr. Ges. Brauw.’ 1914, 37,2. Abst. ‘J. Inst. Brewing,’ 
1914, 20, 136.) 
The colloids of beer migrate towards the cathode. The difference between the 
concentration of hydrogen ions and the acidity of beer as found by titration is dis- 
. cussed. A form of apparatus is suggested for the measurement of ion concentration 
for technical use. 
‘An Account of Some Investigations on the White Winesof South Africa : an Gino- 
logical Study.” Horace T. Brown. (‘J. Inst. Brewing,’ 1914, 20, 345.) 
The white wines of the Cape are peculiarly liable to turbidity or ‘ casse,’ accom- 
panied by an increase in colour and a bitter flavour. ‘Casse’ is not due to micro- 
organisms, but is conditioned by purely chemical changes, and only arises in contact 
with air or with oxygen derived from some such source as hydrogen peroxide. The 
oxidising agent inducing ‘ casse’ does not belong to the class of vegetable oxidases, 
but consistsof a small amount of iron in the ferrous state present in the wine, which 
behaves as a carrier of oxygen (Fenton’s reaction). The ‘casse’ itself consists of 
colloidal particles of a combination of iron with products derived from the limited 
oxidation of tannins and certain proteins present in the wine. The grape contains 
a peroxidase in the inner cells of the epidermis and in the vascular bundles of the 
fruit, but freshly expressed grape-juice contains no peroxidase unless the juice of 
the fruit has remained in contact with the skin for some time. If the amount of 
oxidase in the juice is considerable it has a tendency to brown on exposure to the 
air, but there appears to be no connection between the occurrence of oxidase and the 
_¢easse ferrique referred to above. 
‘Estimation of Colloidsin Beers.’ R.Marc. (‘ Kolloid-Zeitschr.’ 1914, 14. Abst. 
‘J. Inst. Brewing,’ 1914, 20, 431.) 
__ Measurements made by means of refractometer readings before and after adsorp- 
_tion of colloids by barium sulphate. 
“Green Sickness (Verdissement) of Ciders.’ WarcoLzier. (‘Comptes Rendus,’ 
1914, 158, 973. Abst. ‘J. Inst. Brewing,’ 1914, 20, 457.) 
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