65 



With regard to starch solutions and starch pastes, some viscosities 

 have aheady been given. (Report I., p. 47. See especially Samec, 

 1911, KoU. Chrm. Beiheffe, 3, 123-lGO; 1912, idem, 4, 132-174; 

 1913, iiew, 5,, 141-210.) Elsewhere (" The Conditions tJmt Govern 

 Stateness in Bread," 1919) the present MTiter has observed that " the 

 change in viscosity, with time, of starch paste follows a general rule 

 in that, at first thinly viscous when first prepared (hot), it sets to a 

 jelly, and later becomes tkinly viscous again." Pure supsensoids 

 change their viscosities (usually a decrease) in days, the more typical 

 emulsoids showing an increase in viscosity much more quickly. It is 

 assumed that, in starch paste, the latter changes are masked by the 

 slower changes of the former. As a matter of fact, the curve (viscosity 

 plotted against time) is of a distmct S shape, the changes being more 

 marked the more concentrated the solution. The solutions worked 

 with were prepared by digesting 8 grams of wheat starch (containing 

 10-8 per cent, water) in 180 c.cs. of wate:^ and boiling till the clearest 

 paste was obtained. Other figures of interest obtained with such 

 a solution are sho\vn in Table II., but should be compared with those 

 in Table III. showing the same methods applied to Doughs and 

 Bread-crumb, since, in every case, it is clear that the principle under- 

 lying changes in starch paste need not necessarily be reproduced in 

 bread-crumb, in which the phases are so differently distributed. 



Table II. 

 Starch Paste. 



* These values are unreliable, owing to magnification of experimental erior 

 by calculation. 



•f After 150 hours sv still higher figure was obtnined. 



X 11454 



