Procuring Crystallisations in the Dry Way. 315 



bodies with the aluminates of the same formula may be ob- 

 tained artificially, as likewise with the ferrate of iron Fe^ 0^, 

 Fe in all proportions, precisely as they are found in na- 

 ture, a circumstance which has long embarrassed those mine- 

 ralogists who do not well understand the relation of physical 

 and chemical characters. 



Thus isomorphisms which, according to facts of another 

 nature, have hitherto been only probable in regard to siib- 

 stances which we had not the means of causing to crystallise 

 at pleasure, are now found completely established by M. Ebel- 

 men's experiments. 



The reporter states further : The leading idea which M. 

 Ebelmen has conceived, appears to us a richer one than he has 

 represented it to us — no doubt because he wished to speak 

 only of what he had made the subject of experiment, which 

 has already yielded results of considerable importance. In 

 its most general form, the idea consists of this, that many 

 bodies in fusion probably possess the property of acting as 

 dissolvents on many others, fusible as well as infusible. It 

 does not appear absolutely necessary that these bodies should 

 be capable of being volatilised in order to obtain from them 

 a crystallisation of the dissolved substances, for with water 

 only we may obtain crystals in vessels hermetically sealed, 

 and consequently without evaporation, by the mere difference 

 of the temperature of saturation and crystallisation. Now, 

 since we find infusible bodies, such as quartz, corundum, 

 spinel, cymophane, &c., as well as fusible bodies such as 

 garnet, emerald, &c., in felspathic substances, in the granu- 

 lar cai'bonate of lime, &c., may we not suppose that these 

 matters, in a state of fusion, have been the dissolvents ? May 

 we not also suppose the same thing of many others ? These 

 are at least fine subjects for experiment, which it will be of 

 advantage to try ; for if we may suppose, in consequence of 

 M. Ebelmen's experiments, that boracic acid may be the 

 vehicle of some great crystallisation, by way of formation, in 

 some localities whore we at present sec it disengaged in 

 abundance, it must be confessed that this body, as well as its 

 compounds, is too rare among the products that issue from 

 the bosom of the earth to ascribe to it the enormous mass 



