140 Journal of the Mitchell Society \_Decemher 



able lower viscosity sago starcli is quite similar to cassava 

 starch as regards the effect of boiling on the solution. 



Wheat starch shows a gradual increase in viscosity with the 

 time of boiling, similar to corn starch, though the total increase 

 is small, the viscosity of the thirty minute determination being 

 only slightly higher than the determination made at the boiling 

 point. 



Rice starch has the same viscosity as water when measured 

 under these conditions. At the end of thirty minutes boiling 

 it shows only a very slight increase in viscosity. 



The marked differences in the effect of boiling on the vis- 

 cosities of the different starches is due to the fact that some 

 starches form soluble starch products more readily than others. 

 The data given in the preceding table shows very plainly the 

 importance of the viscosity in determining the value of a starch 

 for mill purposes. 



SPECIAL OE TREATED STARCHES. 



A number of special starches are now used which have been 

 treated so as to make them " thin boiling starches," that is, 

 when boiled the solution has a lower viscosity than the natural 

 starches. These usually consist of corn starch which has been 

 treated in some way to reduce the viscosity. The viscosities of 

 several such starches are shown in the following table: 



Table III. — Viscosities oe Special or Treated Starches.'' 

 (i2 grams starch in 300 cc. water, boiled ten minutes.) 

 Starch Viscosity 



Eagle Finishing 1.15 



N Starch alkaline 2.13 



Famous N 1.17 



Erkenbrecher's Modified 1. 13 



T. B. Crystal No. 75 i.ii 



T. B. Crystal No. 90 1.04 



Special Warp Sizing 3.48 



There are quite a number of processes for treating starches 

 to reduce the viscosity or make them thin boiling starches. In 

 the table above the Eagle Finishing Starch is a treated starch 



^ The samples of treated starches were very kindly furnished the author by 

 the Com Products Refining Co., of New York. 



