Prof. Knoblauch on the Deportment of Crystalline Bodies. 35 



A disc of carbonate of lime, in which the particles were brought 

 by pressure more closely together in one direction_, set itself with 

 the line of compression equatorial. This line therefore corre- 

 sponds with the axes of arragonite and calcareous spar. 



The same coincidence was exhibited between a disc of pow- 

 dered carbonate of iron and the crystal of the same substance. 

 The direction of compression, like the axis of the crystal, set 

 equatorial. 



Besides those bodies whose chemical composition is the same 

 as that of the crystals examined, others of powdered glass, chro- 

 mate of lead, and phosphate of lime were also submitted to ex- 

 amination. Of conducting bodies, oxide of manganese, oxide of 

 iron, antimony and bismuth, were examined; the direction of 

 compression in all these substances set itself between the electric 

 poles equatorial. 



The decided manner in which these pheenomena are exhibited, 

 prove to a certainty that those bodies in which the material par- 

 ticles are not the same distance apart in all directions set between 

 the poles (when the directing influence of mere shape is annulled), 

 so that the line in which the particles stand most closely together 

 stands equatorial. 



The coincidence of position of diamagnetic crystals between 

 the magnetic and the electric poles, and the difference of position 

 assumed by magnetic crystals, stand in immediate connexion 

 with the results arrived at by Mr. Tyndall and myself. We have 

 shown that, in bodies whose particles are unequally separated in 

 different directions, that direction in which the particles lie most 

 closely together sets in the magnetic field when the substance is 

 magnetic from pole to pole ; when the substance is diamagnetic, 

 equatorial. 



Of the crystals mentioned the following are magnetic : — car- 

 bonate of lime and iron, beryl and tourmaline. In all these 

 cases, that direction, which, by the action of the magnetic poles, 

 sets itself axial, between the electric poles sets equatorial. 



Of the crystals examined the following are diamagnetic : — 

 heavy spar, sulphate of lime, saltpetre, Iceland spar, arragonite 

 and bismuth ; in all these cases, the direction which between 

 the magnetic pole stands equatorial, takes up the same position 

 between the electric poles. 



The principal results of the inquiry may be expressed as fol- 

 lows : — 1. Crystals, conductors and non-conductors, under the 

 influence of the electric poles obey a directive force which is in- 

 dependent of the form of the mass. 2. The same is the case 

 with bodies the material particles of which are brought by pres- 

 sure into unequal distances from each other ; that line in which 

 the particles lie most closely together being caused to recede 



D2 



