HOW MOLECULES MAKE MASSES 55 



substances where adsorbed layers cause particles to cohere. In starch 

 grains, the less soluble amylopectin seems to coat over the more soluble 

 amylose; but the resolubility of dried boiled starch paste indicates that 

 there conditions are reversed. 



Calcium seems to play an important role in establishing the co- 

 herence of particles in aqueous media. Thus lime in soils aids in 

 bringing them into a condition of good tilth, described by Sir. E. J. 

 Russell as that "nice crumbly condition suitable for a seed bed." 

 On the other hand, alkaline soils dcflocculate and puddle badly. 

 Calcium humate appears to act as a cohesive colloid, especially 

 when the soil dries out, and thus incidentally prevents the winds 

 from blowing away the valuable top soil. The economy of China 

 is affected by such losses, and "Peiping throat" is caused by breath- 

 ing the begrimed air. A great dust storm swept over New York 

 on May 12th, 1934; and it is estimated that 300,000,000 tons of 

 soil were lifted from drought-parched Western States by a strong 

 northwest wind, and scattered over half of the United States. 

 It must also be recalled that Professor C. Herbst (Heidelberg), 

 who died in 1946 at the age of 80, had found many years ago that, 

 in the absence of calcium, the cells developing from fertilized 

 sea-urchin eggs fail to cohere, and normal development is frus- 

 trated. 



The work of Wanda K. Farr and collaborators 29 indicates that 

 cellulose contains ellipsoidal crystallites about 1.5 microns long 

 and 1.1 microns wide, cemented together by a pectinous material. 

 The passage of the much-needed and beneficial Pure Food and 

 Drugs Act in 1906 was largely due to the efforts of Dr. Harvey W. 

 Wiley, Chief Chemist of the U.S. Department of Agriculture. 

 Flushed with deserved victory, he began soon thereafter to issue 

 what he considered to be "standards" for many foods. He ex- 

 tended these rulings to such confections as ice cream, which he 

 declared should contain nothing but cream, sugar and flavor, the 

 latter including fruits and nuts. Faced with the fact that pro- 

 tective colloids (eggs, gelatin, gum, etc.) had commonly been 

 used in making satisfactory ice cream, and also in candies like gum- 

 drops, Wiley held that French ice-cream, always made with eggs, 

 should be sold under the name "frozen custard." He then insti- 

 gated a test case against a small ice-cream maker in Washington, 

 which was defended by the National Association of Ice Cream 

 Manufacturers. After hearing the evidence on both sides, the 

 Court directed a verdict of "not guilty" in what I am told was the 



