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THE 



AMERICAN JOURNAL OF SCIENCE 



[THIRD SERIES.] 



Art. XX. — On Gold-colored Allotropic Silver; by M. 

 Carey Lea. (Part I, with 3 Plates.)* 



The object of the present paper (which may be considered 

 as a continuation of that published in this Journal for June, 

 1889) will be : 



1st. To describe the reactions of gold-colored allotropic 

 silver. 



2d. To show that there exists a well characterized form of 

 silver intermediate between the allotropic silver previously 

 described and ordinary silver, differing in a marked way from 

 both. 



3d. To prove that all the forms of energy act upon allotropic 

 silver, converting it either into ordinary silver or into the 

 intermediate form. Mechanical force (shearing stress) and 

 high tension electricity convert it directly into ordinary silver. 

 Heat and chemical action convert it first into the intermediate 

 form, then into ordinary silver. The action of light is to pro- 

 duce the intermediate form only, and even the most prolonged 

 action at ordinary temperatures does not carry it beyond this. 



4th. To show that there exists a remarkable parallelism 

 between the action of these forms of force on allotropic silver 

 and their action on the silver haloids, indicating that it is not 

 improbable that in these haloids silver may exist in the allo- 

 tropic condition. 



Reactions, 



The most characteristic reactions of gold-colored allotropic 

 silver are those with the strong acids. When normal silver 



* Numbered I, II, III, being Plates XI, XII, XIII of the volume. 



Am. Jour. Sci. — Third Series, Vol. XLI, No. 243.— March, 1891. 

 12 



