OUR WATER SUPPLY— MEINZBR 293 



intervals and with high latent heat in passing from one state to an- 

 other, lend themselves so remarkably to the needs of civilized man 

 in his multitudinous domestic and industrial operations, recreational 

 activities, and therapeutic applications that it seems as if these prop- 

 erties had been providentially designed for the benefit of man. It is 

 an interesting exercise to make a list of the uses to which water is 

 put by man, many 'of wliich are analogous to the physiological uses 

 of water by living organisms, as for example, the conveyance and 

 storage of material and energy, often with resultant chemical changes, 

 the regulation of temperature, and the elimination of waste. It will 

 be noted that in most of these uses, water serves as the vehicle for 

 conveying either matter or energy. It is not surprising that water 

 has acquired a unique religious significance as the symbol, in the rite 

 of baptism, of spiritual cleansing and regeneration by the washing 

 away of all sin. 



The average per capita consumption of water in the cities and 

 towns of the United States amounts to more than 100 gallons a day. 

 Some of this water is wasted but most of it is used for beneficial pur- 

 poses. In the future the volume so used will be increased and new 

 uses will be developed. Thus, the rapid advance in air conditioning 

 of buUdings is producing an almost alarming increase in the demand 

 upon our public water supplies. It may therefore be expected that, 

 even with reduction in waste, the consumption of water will increase 

 with advancing civilization. One of the truly great achievements of 

 civilized man is that of providing, for human use, abundant, con- 

 venient, and reliable supplies of water of good quality. Indeed, the 

 improvement of the quality of the water supplies has been a major 

 factor in increasing the average length of human life. However, con- 

 sidering the less advanced countries of the world and the rural sec- 

 tions of our own country, it is evident that the task is still far from 

 being completed. 



The ultimate water supply. — The great residual reservoir of water 

 is the ocean, which contains aU except a small percentage of the 

 external water of the earth, the rest being on the surface of the land, 

 or in the interstices of the soil and rocks, or in the atmosphere. It is 

 necessary to distinguish between the external and the internal water, 

 for there is evidence that water is one of the constituents of the 

 magma that forms the interior of the earth, and the total quantity 

 of this internal magmatic water may be very great. The supply of 

 external water is apparently being augmented by the extrusion of in- 

 ternal water and possibly by acquisition from outer space. There 

 are also processes in operation which release water from chemical 

 combination, but these are compensated more or less by processes 

 which tie up some of the existing external water. Any attempt to 

 evaluate these several processes would be quite academic. It appears 



