Serendipity, Lithium, and The Affective Psychoses

To the Editor:—  It is remarkable how often serendipity plays a role in scientific discovery, especially in the field of medicine. I enjoyed reading Levy's paper concerning the use of lithium salts in the treatment of affective psychoses.¹ I was somewhat disappointed, however, in his not mentioning the fascinating story of how Cade came upon the idea to use lithium in the treatment of manic-depressive disorders. As Cade himself describes it:In the course of some investigations by the writer into the toxicity of urea when injected intraperitoneally into guinea-pigs, it appeared desirable to ascertain whether uric acid enhanced this toxicity. The great difficulty was the insolubility of uric acid in water, so the most soluble urate was chosen— the lithium salt. When an aqueous solution of 8% urea, saturated with lithium urate, was injected, the toxicity was far less than expected. It looked as if the lithium ion