384 /. D. Dana on Cohesive Attraction. 



active states, — the former changing to the latter under the action 

 of light or the chemical rays, — will be different states induced 

 by or through rapidity of pulsation, the rapid pulsation of mole- 

 cular force (causing or constituting what we call chemical rays) 

 inducing the same rapid action in molecules under their influ- 

 ence. Magnetism may be a condition in which the attractive 

 force is in constant active onward transfer from particle to particle, 

 and galvanism, a condition of similar transfer while an exciting 

 cause is in operation. 



In hemihedral prisms like those of tourmaline and topaz, 

 the molecules must have been in this magnetic condition ; for they 

 exhibit polarity now when heated. In the right and left handed 

 quartz and similar cases, where while forming one side of a 

 molecular pole must have been differently affected from the op- 

 posite, we may believe that the pulsations were alternate along 

 each axis, a, 6, c ; this would in fact be a spiral action and it 

 would produce a right and left handed crystal, according as the 



spiral action was to the right or left. 

 We 



eneral 



„_ -. w^ *»*, i*a^ix y M^vj. ^AV^CtlCAL O HC'iCJ OtCltVyvA. WILLI lliv tv**^^ 



theory of molecules and molecular forces presented lately, with 



Whelpley 



? 



^-'vWV^V/ v lLvlli 



The explanations offered show that very many of the phe- 

 nomena of physical nature, mav be understood on the idea that 

 molecules are simply centres of attraction, the same attraction 

 whose laws have been under consideration. But no property of 

 cohesive attraction explains the limits and proportions observed 

 in chemical combination. The ultimate nature of the molecule, 

 or of the forces constituting them, (on which we forbear from 

 remark in this place.) is our only appeal for an explanation of these 

 chemical relations. When fnllv i, n ^o™tn^ it mav annear that 



cohesive attraction with all its laws, is only a necessary result of 

 this peculiar constitution. We need yet some facts to make it 

 obvious how both classes of phenomena, those of aggregation 

 and chemical combination, may be united in one continued series. 



These theoretical suggestions on molecules are annexed to 



pai 



— „_ 1B _, MU , jjo-tuy in elucidation oi sume u*.^™ --- 



stated, but more especially to exhibit the bearing of the principles 

 on different theories respecting the constitution of matter, ana 

 to show that what may seem to be discrepancies are not ne- 

 cessarily so. 



There is a strange variance between the chemist and crystallo- 

 grapher. In treatises on chemistry, a theory r* — , ~" l]flr ton ™ 



taken 



rystals 



