Uncryslattized Mineral Subxtances. 357 



100 specimens from Sweden, permitted me to select from his collection 

 the forms which appeared to be of most scientific interest. It is this rich 

 and fine .collection of forms, with all the circumstances of development, 

 and coming from one and the same deposit, that I have now the honour 

 to present to the Academy for inspection. 



But I have found a much richer source of materials in the microscopic 

 examination of the primitive phenomena presented by the structure of in- 

 organic forms ; and these are the materials which have become so im- 

 portant as to form the basis of all my labours. For several years past, 

 the observations of this nature made by me have been published and dis- 

 seminated, and 1 have already, in 1836, published in Poggendorffs An- 

 nals the most remarkable results of my researches on the formation of 

 crystals. 



The results of my observations on these forms, and the analytical re- 

 searches I have made, shew at once that it is convenient to establish in 

 all the phenomena of inorganic form, after excluding crystals, several 

 groups entirely distinct from each other. 



One of the groups of these structures, named amorphous or irregular, 

 embraces all the dendritic, capillary, stalactitic, and radiated forms, with- 

 out nucleus and similar to hcematite, and those with a radiated-oolitic 

 structure, having a foreign nucleus, and which may be regarded as true 

 crystals confounded together, bearing the same relation to simple and 

 distinct crystalline forms that the massive and composite polypi present 

 relatively to the simple polypi. In these two cases the individual forms 

 have no connection with the shape of the united mass, and reciprocally. 

 These structures, sometimes easy, and at other times very difficult to 

 analyze by the aid of the microscope, arc agglomerations of small crystals 

 more or less conformable, and following certain laws, in some cases capable 

 of being recognised, and which, in relation to the variety or the regula- 

 rity, make an approach to those of the structure of plants founded on 

 the development of the bud. All these forms are not crystalloids, but 

 masses of crystals, or well-determined crystals heaped together gcnerically, 

 the forms of which, compressed and crushed, arc called druses when the 

 crvstab can be easily observed, and, when the structures arc less dense 

 and more delicate, produce dendritic figures in the shape of a shrub, moss, 

 tree, &c. 



The Egyptian morpholites, the Imatra stones of Finland, and those of 

 the malrckor of Sweden, are entirely different in their structure from those 

 just mentioned. These bodies present neither any radiation from the 

 centre, nor any appreciable crystalline development in their parallel 

 planes of formation. They exhibit in their structure, on the contrary, 

 and in a very obvious manner, a solid circle which is several times re- 

 peated, an evidently active development in their formation, founded on 

 uniform laws, and frequently, perhaps always, as is seen in the Tunaberg 

 specimens, parting from many axes of formation. No trace of organic 

 structure, whatever may bo the exterior aspect, is ever remarked in any 



