L. J. HENDERSON, W. O. FENN, AND E. J. COHN 391 



4.0 



S.O 



6.0 



7.0 



SO 



Fig. 2. 



of the observations and, as we believe, justify such use of them in 

 drawing conclusions as is at present necessary. 



Efect of Hydrogen Ion Concentration upon the Viscosity of Dough. 



Our first series of experiments concerns the influence of hydrogen 

 ion concentration upon the viscosity of dough prepared from four 

 different flours. Differences of reaction were produced by the addi- 

 tion of solutions of hydrochloric acid and sodium hydroxide and esti- 

 mated with the help of the concentration cell. The varied character 

 of the four flours is indicated by the difference in the water content of 

 their approximately iso viscous doughs. 



The results clearly show that a single measurement of viscosity 

 possesses no great significance (Table I and Fig. 2). Nevertheless 

 it is evident that with variation in hydrogen ion concentration vis- 

 cosity passes through a minimum a little on the acid side of pH 5. 

 Jessen-Hansen^ has found pH 5 to be the best hydrogen ion concen- 

 tration in bread making and it is also, as we have observed, the 

 most favorable reaction for the rising of dough. 



^ Jessen-Hansen, H., Compt. rend. trav. Lab. Carlsberg, 1911, v, no. 10. 



