PROCEEDINGS 



OF THE 



WASHINGTON ACADEMY OF SCIENCES 



Vol. VII, pp. 257-366. July 24, 1905. 



ON BASIC SUBSTITUTIONS IN THE ZEOLITES. 

 By F. W. Clarke. 



During the past 7 or 8 3'ears a number of researches upon 

 the constitution of the natural silicates have been carried out in 

 the laboratory of the United States Geological Survey. Some 

 remarkable results have been obtained ; and it is now seen that 

 the zeolitic minerals exhibit a high degree of chemical plas- 

 ticity. Sodium and calcium are easily withdrawn from them, 

 and replaced by other metals or basic radicles ; and some of the 

 more striking examples of these reactions are already on rec- 

 ord. In Survey Bulletin 207, for instance, a number of am- 

 monium substitution derivatives are described, such as am- 

 monium analcite, ammonium natrolite, and so on. In Bulle- 

 tin 262, data are given concerning silver and thallium salts of 

 similar character, and the list might be extended almost indefi- 

 nitely. A large and novel field of investigation is now open, 

 which is not likely to be soon exhausted. 



In addition to the compounds just mentioned, a number of in- 

 teresting sodium, strontium and barium derivatives have been 

 prepared and studied during the past year by Mr. H. C. JNIc- 

 Neil. His work will be published in detail, later; the present 

 communication gives only a summary of his results, together 

 with some theoretical discussion. A few of Mr. Steiger's prep- 

 arations are also cited, for purposes of comparison, and to illus- 

 trate the range of the observations. 



The mineral analcite has proved to be peculiarly susceptible 

 to transformation, and has yielded derivatives most easily. 

 They may be tabulated as follows : 



Proc. Wash. Acad. Sci., July, 1905. 



