44 LIFE: ITS NATURE AND ORIGIN 



toes), the pH may be closer to alkalinity and become favorable to the 

 growth of some micro-organisms. Thus, the fungus Tinea, which 

 causes "athlete's foot" commonly grows between the toes, and may be 

 combatted by acid germicidal ointments containing, e.g., salicylic acid 

 and sulfur; and the highly acid sulfate of alumina is the basis of most 

 cosmetics used to combat under-arm odor. So old is this custom that 

 the elder Pliny (Gaius Plinius Secundus), the Roman encyclopedist 

 who perished while investigating the great eruption of Vesuvius which 

 buried Pompeii and Herculanium in 79 A.D., mentions in his "Natural 

 History" 3 that "alum is used for offensive odors in the axilla." In the 

 stomach the gastric juice has an acidity of between pH2 and 3, corre- 

 sponding to about 0.1 to 0.2 per cent hydrochloric acid. In some 

 snails and ascidians (e.g., Phallusia), the blood may be quite acid. 



Water has one other peculiarity which is generally overlooked, 

 namely, the tendency of its molecules to form groups, probably in 

 part through hydrogen bonds. This phenomenon, common to 

 many other substances 4 is known as molecular association; and 

 water contains double and triple molecules (dihydrol and tri- 

 hydrol) whose percentages vary with conditions. According to 

 N.E. Dorsey, 5 many accept the quasi-crystalline theory of water 

 structure sponsored by J. D. Bernal and R. H. Fowler 6 and M. L. 

 Huggins, 7 which demands a fairly rigid structure for water. But 

 it must be remembered that, apart from whatever structure water 

 may assume as the result of a kinetic equilibrium of its ions and 

 molecules, a supermolecular structure may at times appear at 

 levels higher than those before mentioned. Thus Professor H. T. 

 Barnes of McGill University, in speaking of frazil — a type of ice 

 occasionally giving much trouble to users of hydraulic power 

 by obstructing the flow of water like the slimy precipitates met 

 with in chemical analysis — says that when first formed it is too 

 fine to be seen by the eye, apart from its action on the color of the 

 water. But it soon agglomerates into spongy masses of loose tex- 

 ture, which readily catch onto subjects in the water, and quickly 

 build large masses. The slightest drop in temperature below 

 0° C may cause frazil to appear. "The balance is so delicate that 

 it will escape detection by the most sensitive thermometer and the 

 first indication that a drop has occurred will be the appearance of 

 ice." The action of frazil on the appearance of the water brings 

 to mind the familiar glooming or darkening of clouds when rain 

 impends. 



It is pertinent here to quote the remarks of Thomas Graham (1861): 

 "Ice itself presents colloidal characters at or near its melting point, 



