598 BELL SYSTEM TECHNICAL JOURNAL 



differs from previous methods used for growing large single crystals from 

 solution, in that the solution saturated at one temperature is continuously 

 fed into a crystallizer tank maintained at a slightly lower temperature, thus 

 providing the supersaturation condition necessary for crystal growth. Fur- 

 ther, the solution is circulated in such a manner that the partially im- 

 poverished mother liquor overflows from the growing tank back into the 

 saturator where it is refortiiied and filtered. It is then heated and returned 

 to the growing tank in such a way as to avoid the formation of undesirable 

 crystal nuclei. 



The paper contains a description of the new method which is now in 

 commercial operation, together with a general discussion of some of the 

 important principles involved in the successful growth of large single crystals 

 of water soluble salts. 



Crystal Fillers Using Ethylene Diamine Tartrate in Place of Quartz}'^ E. S. 

 Willis. Ethylene diamine tartrate (EDT) crystal filters were developed to 

 replace the earlier quartz type channel filters in the broad-band carrier 

 telephone systems, because of the threatened scarcity of quartz. These new 

 filters give performance comparable to that of the earlier design. The growth 

 of the EDT crystals from seeds and their fabrication into crystal units for 

 use in filters are covered in companion papers on "Design and Performance 

 of Ethylene Diamine Tartrate Crystal Units" and "Growing Crystals of 

 Ethylene Diamine Tartrate" in this same volume of the Transactions 



iM. /. E. E. Transactions, v. 67, pt. 1, pp. 552-556, 1948 



