Ball — On the Action of Peetase. 357 



Summary. 



1. During the action of peetase on a solution of pectin the electrical 

 conductivity of the mixture remains practically constant, showing tljat a gel 

 is formed, and not merely a very viscous liquid. 



2. The changes in viscosity during coagulation were determined by means 

 of a viscosimeter of the Ostwald type. By comparison of experiments at 

 C. and 14° 0. the activity of the enzyme was found to be very much 

 greater at the higher temperature. 



3. Tiie viscosity was found to increase slowly at first, then more rapidly 

 until a maximum was reached, and this was followed by' a rapid decrease. 

 Increase in the amount of electrolytes present lowered the maximum, while 

 a decrease in the electrolytes raised it. The decrease in viscosity is probably 

 to be explained by the action of the electrolytes in clumping together the 

 particles of colloid forming tlie reticulum of the gel, so that a suspension is 

 produced. 



I am indebted to Dr. W. R. Gr. Atkins, both for having originally 

 suggested the nature and methods of this research, and for many valuable 

 suggestions while the work was in progress. 



I am also indebted to Professor H. H. Dixon for the benefit of his 

 advice on many portions of this work. 



Bibliography. 

 (1) Bertrand et Mallevre. — Sur la peetase et sur la fermentation pectique. 



Compt. Eend., 1894, cxix, 1012. 

 (2) Nouvelles recherches sur la peetase et sur la fermentation 



pectique. Compt. Eend., 1895, cxx, 110. 

 (3) Sur la diffusion de la peetase dans le regno vegetal et sur 



la preparation de cette diastase. Compt. Eend., 1895, cxxi, 726. 



(4) BoTJRQUELOT. — Sur les pectiues. Journ. de Pharm. et de Chim., 1899, 



ix, 563. 



(5) BouRQUELOT et H£rissey. — De Taction des ferments solubles sur les 



produits pectiques de la racine de gentiaue. Journ. de Pharm. et de 

 Chim., 1898, viii, 145. 



(6) Sur la pectine de Cynorrhodon. Journ. de Pharm. et de 



Chim., 1899, X, 5. 



(7) Browne, C. A. — Handbook of Sugar Analysis. New York (John 



Wiley & Sons), 1912. 



(8) Eulek, H. — Greneral Chemistry of the Enzymes. English Translation 



by T. H. Pope, New York (John Wiley & Sous), 1912. 



(9) Fremy. — Eecherohes sur la pectine et I'acide pectique. Journ. de Pharm., 



1840, xxvi, 368. 



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