I9I4] 



A. W. Thomas 



405 



On Dec. 15 the starch was placed in an oven to dry. Unfor- 

 tunately it was too wet and some of it jellied. It then had to be 

 slowly dried until Dec. 22, when it was ground up to 100 mesh and 

 put into distilled water for a day's further washing. On Dec. 23 

 drying before a fan was started and on Dec. 27, after the process 

 had been completed, the product was placed in an oven at 105° C. 

 for 4 hr., and then bottled (Sample E.) 



This final soluble starch product was so pure that it could not be 

 precipitated from water by alcohol. A 3 percent sol. was made by 

 adding the required amount of paste to boiling water and then cool- 

 ing. To some of this sol. an equal vol. of alcohol was added with the 

 result that a milky Suspension but no separable precipitate was 

 formed. Ordinary soluble starch is precipitable by alcohol due to 

 the presence of electrolytes as impurity. Traces of electrolyte 

 cause precipitation. In order to see what the behavior of the phos- 

 phorus Compound would be, a drop or two of 10 percent sodium 

 chlor id sol. was added to 200 cc. of 3 percent sol. and then the starch 

 was precipitated by means of 200 cc. of alcohol. About 2.5 gm. 

 were obtained. This precipitate (Sample F) was dried and analyzed 

 for phosphorus. The phosphorus figures are summarized below: 



It is interesting to note that E contains 0.0168 percent of phos- 

 phorus. This starch gives a true colloidal dispersion in water which 

 is not precipitable by alcohol; evidence that very little if any elec-i 

 trolyte is present. Therefore, all the phosphorus cannot be present 

 as H3PO4 as Fouard claims, and our only other assumption can be 

 that the phosphorus is present in some un-ionized form, i. e., in 

 organic combination with the starch. 



It is also of interest to note that Sample F, the electrolyte-alcohol 

 precipitate of a Solution of E, contains (within the limits of experi- 

 mental error) practically the same amount of phosphorus as Sample 

 E. This would seem to bear out our point that the phosphorus is 

 not all occluded as phosphoric acid. If it were only mechanically 



