BRIEFER ARTICLES 



A METHOD FOR PRODUCING CONDUCTIVITY WATER 



SUITABLE FOR WATER CULTURE EXPERIMENTS 1 



(with one figure) 



An examination of one of the most recent types of water stills has 

 convinced the author that there is abundant opportunity for the presence 

 of copper and other metals in the distillate. The boiler is made of 

 copper, not completely covered by tin; consequently, a coating of cop- 

 per carbonate forms which may be conducted over in the spray during 

 rapid distillation. Although the condenser itself may be of block tin, 

 there is ample opportunity for contact of the distillate with brass con- 

 nections. 



On account of the reputed great physiological activity of copper, it 

 was deemed advisable to use water free from the suspicion of contami- 

 nation. This led the author to devise a method for producing water of 

 high resistance in sufficiently large quantity for water culture experi- 

 ments. The apparatus here described has been used for some time and 

 has been found entirely satisfactory. 



The level of water in a tubulatured retort is regulated automatically 

 by a siphon (i) which discharges to a constant level in receiver (3). The 

 end of the water tube (2) of the regulator is so adjusted that air can rise 

 into the reservoir above only when the level in the retort is lowered 

 slightly by distillation. Then the vacuum pressure is relieved slightly 

 so as to allow water to flow into the siphon. 



It was found necessary to provide the water seal siphon with an 

 upright tube to prevent the stoppage of the siphon by gases expelled 

 from the water when heated. 



the 



cr 



minimize 



— *— / J* 



being carried over. A pledget of glass wool is placed in the bent neck 

 of the retort to remove spray and return it to the retort. Condensation 

 of the distillate is affected by a glass water jacket fitted to the neck of 

 the retort by rubber stoppers. 



1 Published by permission of the Secretary of Agriculture. 



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