Apeil 7, 1922] 



SCIENCE 



361 



sumed in this condition but nowadays is oft^n 

 further purified by washing and reerystalliza- 

 tion so that the iodine, which is in very low 

 concentration in the sea water, is reduced to 

 infinitesimal quantities. Salt was not purified 

 to as great an extent in the early days as it is 

 now. When it comes to rock salt Nature has 

 already purified it to some extent. Van't Hofl: 

 showed the mechanism of stratification of the 

 rock salt deposits. The sodium chloride layers 

 are already more or less purified. This salt 

 when it is mined in the dry state or when it is 

 obtained from salt springs, which consist of 

 water which has come in contact with these salt 

 deposits, is still further purified for table use. 

 Hayhursf^^ investigated some of the salt works 

 in Ohio where the salt is obtained from deep 

 wells. Bromine and a trace of iodine are sep- 

 arated out of the salt and the bromine sold as 

 a by-product. 



I have been unable to obtain any evaporated 

 sea water, that is to say, salts obtained from 

 the sea water without fractional precipitation 

 or purification, from any commercial salt 

 manufacturers on the coast. Through the 

 kindness of Metz & Company, Dr. Sherndahl 

 evaporated 100 gallons of sea water for me to 

 use in experimental feeding. This, together 

 with sea water which I have had opportunity 

 to evaporate, has been dried by baking it in 

 an oven. When the last traces of water are 

 eliminated in this way, hydi-ochlorie acid fumes 

 are also given off. The cause of this, as point- 

 ed out by Sorensen, is a reaction between mag- 

 nesium and the other salts whereby oxides of 

 the alkaline earth metals are formed with the 

 elimination of hydrochloric acid. If the baking 

 is continued long enough no caleiiun or mag- 

 nesium chloride remains and therefore the salt 

 remains dry. If the sea water has been evap- 

 orated in an iron kettle some iron oxide is 

 added to it, which improves it from a nutritive 

 standpoint. The necessity of baking may be 

 eliminated by adding 6 gi-ams of HgPO^ to the 

 liter and this salt may aid in the treatment of 

 rickets. In my animal experiments this evap- 

 orated sea water has been used for generations 

 of animals as the salt ration, with gratifying 

 results. It is very low in phosphoric acid 



" Hayhurst, E. E., Science, 1921, liv: 131. 



unless HgPOj has been added, and if casein is 

 used as the protein there is not sufficient phos- 

 phoric acid in the casein for the nutritional 

 requirements. The question as to whether 

 there is sufficient calcium or not for the total 

 calcium ration has not been definitely settled. 

 If wheat flour is used for the carbohydrate 

 portion of the rat;ion there is sufficient addi- 

 tional calcium in the wheat flour to bring the 

 calcium up to the requirements. 



The question arises whether it would not be 

 advisable for us to feed our children an im- 

 pure salt. If iodine is the only mineral con- 

 stituent that might be deficient it could be 

 easily added to the salt. We have not proved, 

 however, that the other mineral constituents of 

 sea water are not necessary in the diet. There- 

 fore, it would seem much simpler to use evap- 

 orated sea water as the salt ration if it could 

 be obtained, and it only remains to create a 

 demand for it. The present process of com- 

 mercial evaporation of sea water could be 

 simplified if an impure salt was desired. That 

 is to say, only one pond would be necessary 

 for the evaporation of the sea water. Sea 

 water could be evaporated in this pond as far 

 as practical by the sun. The total contents of 

 this pond, including both solids and liquids, 

 could then be removed and evaporated by heat 

 and thoroughly mixed, and baked at a high 

 enough temperature to produce a dry salt. In 

 ease the crystals of salt were large, owing to 

 the slow evaporation at first, they could be 

 ground. In baking, however, there is a ten- 

 dency for these crystals to break up. The 

 inclusion of a little earth with the salt would 

 not impair its nutritive qualities and the 

 product would be sterilized by the high tem- 

 perature used in baking. It has been shown 

 that salt obtained by the usual methods from 

 the salt evaporating plants on the French coast 

 is reeking with bacteria. The production of a 

 sterile product might be an advantage. The 

 dietary salt of several adults, children and 

 infants has been limited to the above described 

 from Metz for many months with gi-atifying 

 results, in a goiterous region. 



J. F. McClendon 

 The Laboeatoet of 

 Physiological Chemistet, 

 Univeesity op Minnesota 



