DRINKING WATER FROM SEA WATER — CONSOLAZIO, ET AL. 157 



droxide. Uric acid was then added to the filtrate, precipitating so- 

 dium urate which was filtered off. 



The method was developed at the Naval Medical Research Institute 

 with field application primarily in mind. Two simple plastic bags 

 and two filters were designed so that minimum space was occupied 

 by these processing devices. The silver oxide was dispersed into the 

 sea water contained in one of the plastic bags. The contents were 

 then filtered into the second bag and the uric acid was dispersed into 

 the filtrate. A final filtration into the first bag, which had been rinsed 

 with sea water, produced potable water. The time required for the 

 complete operation was approximately 30 minutes. The produced 

 water, from a physiologic standpoint, was excellent but the taste al- 

 though not objectionable was slightly brackish. 



The method produced 7.4 volumes of water per unit volume of 

 apparatus, a high ratio. The weight ratio, 5.6 of water to 1 of appara- 

 tus, also represented a very substantial improvement over other 

 methods. 



The standards for drinking water for life-raft use had initially been 

 set empirically to meet the Treasury Department standards (13). 

 These standards were unnecessarily exacting for water that was to 

 be used for emergency purposes as they were adopted by the Treasury 

 Department on June 20, 1925, for drinking water and culinary water 

 supplied by common carriers in interstate commerce. The attempt to 

 meet these impractical and unphysiological standards was unfortu- 

 nately one of the prime factors in limiting the chemical methods since 

 the exacting demands lowered the weight and volume ratios. 



The first approach to the problem of increasing the efficiency of the 

 chemical methods was to determine how much salt could be left in 

 drinking water. Two groups of men were placed on a semistarvation 

 regime (14) (15) and allowed 500 milliliters and 1,000 milliliters of 

 water per day. One half of each group had its water slightly salted 

 (0.3 to 0.4 grams of sodium chloride per 100 milliliters), the other 

 half drank distilled water. The men drinking distilled water excre- 

 ted between 3 and 4 grains of sodium chloride daily. The group 

 drinking 500 milliliters of slightly salted water conserved 100 milli- 

 liters of water per day more than the comparable 500-milliliter group 

 that drank distilled water. The group drinking 1,000 milliliters of 

 slightly salted water conserved 230 milliliters of water per day more 

 than the group that drank 1,000 milliliters of distilled water. By al- 

 lowing 0.3-0.4 percent salt to remain in drinking water a consider- 

 able reduction was made in the daily water requirement. Further- 

 more, considerable reduction was made in the chemical required for 

 producing potable water. 



676212 — 46 11 



