146 M. Savart on the Elasticity of crystallized Bodies. 



mechanical division. It is equally natural to suppose, that less 

 imperfect notions than we at present possess of the elastic state 

 and cohesion of crystals, may throw light on many of the pe- 

 culiarities of crystallization. It is not impossible, for example, 

 that the degrees of elasticity of a given substance may not be 

 exactly the same, and in the same direction relative to the pri- 

 mitive form, whilst from another cause the secondary form is 

 different ; and if this is the case, as some facts induce me to 

 suppose, the determination of the elastic state of crystals will 

 lead to the explanation of the most complicated phenomena 

 of the structure of these bodies. It appears to me indeed, that 

 the comparison of the results obtained by means of light respect- 

 ing the constitution of bodies, and also by means of sonorous 

 vibrations, will necessarily unite in advancing the science of 

 optics as well as that of acoustics." 



Observations by the Editor. 

 . With the greatest deference to the distinguished talents of 

 M. Savart, we suspect that he is mistaken in his views respect- 

 ing the cleavages of carbonate of lime. We have not only 

 never heard of any cleavage in the direction of the lesser dia- 

 gonal of its rhomboidal faces, but we have sought for it in vain 

 by processes which could not fail to have exhibited it. The 

 cleavage too in the direction of the greater diagonal, and of 

 which M. Savart observes carbonate of lime is often suscepti- 

 ble, is, as we have often shown, a face of composition, though 

 in crystals not compounded there is a weakness of cohesion, 

 or what may be called a secondary cleavage in that direction, as 

 rendered visible by the method explained in a former number 

 of this Journal. * Carbonate of lime is always susceptible of 

 this secondary cleavage, and only sometimes susceptible of the 

 composition cleavage, which must be that referred to by M. 

 Savart. If his analysis, therefore, has been made with com- 

 pound crystals, we hope he will repeat it with plates of crystals 

 which he has determined to be simple ones by optical examina- 

 tion. 



We would beg to suggest to M. Savart the following topics 

 for investigation • — 



" See this Journal, No xviii. p. 311. 



