S20 Intelligence and Miscellaneous Articles. 



almost instantaneous ignition of the mass occurs ; but it continues for 

 a much shorter time than with the tartaric acid, because the oxalic 

 acid contains less carbon. In order to obtain a pyrophorus with citric 

 acid, 1 atom of citric acid, previously fused and kept some time in 

 fusion, then dried and pulverized, must be promptly mixed with 

 2 atoms of peroxyd of lead at the temperature of 73° Fahr. The 

 ignition of the whole mass is almost as vivid, and continues for as 

 long a time as with tartaric acid. Minium, litharge, and carbonate 

 of lead, mixed with tartaric acid, yield also, according to M. Boetli- 

 ger, pyrophori, but not so good as those yielded by the pure oxyd. — 

 V Institute March 1, 1837. 



TIVE TO THE LAWS OF MOLECULAR ACTION. 



A translation of the memoir by M. Mossotti " On the forces 

 which regulate the internal constitution of bodies," in which 

 he has embodied the results on this subject which he has hi- 

 therto obtained, has already appeared in Part III. of the *' Scien- 

 tific Memoirs." As, however, the principal result of his labours, 

 — the mutual identification of the attractive forces of electricity, 

 aggregation and gravitation, — constitutes one of the most remark- 

 able discoveries of the present aera in science, we think it desirable 

 to notice it in the Philosophical Magazine, as a matter of reference. 



While reflecting on the Franklinian hypothesis for explaining the 

 phaenomena of statical electricity, as reduced by iEpinus to the form 

 of a mathematical theory, and with the addition subsequently made 

 by Coulomb, proving that electrical attractions and repulsions are 

 regulated by the law of the inverse ratio of the square of the di- 

 stance, M. Mossotti conceived the idea, that if the molecules of 

 matter, surrounded by their atmospheres, attract each other when 

 at a greater, and repel each other when at a less distance, there 

 must be between those two distances an intermediate point at 

 which a molecule would be neither attracted nor repelled, but would 

 remain in steady equilibrium ; and that it was very possible that this 

 might be the distance at which it might be placed in the composition 

 of bodies. Learning subsequently that the attention of geometers 

 had recently been particularly directed to the molecular forces, as 

 being those which may lead us more directly to the knowledge of the 

 intrinsic properties of bodies, he was thus led to recall his ideas on 

 the subject, and to set about subjecting them to analysis, and he has 

 submitted to the judgement of philosophers, in the memoir here re- 

 ferred to, the results of his first investigations. Of the contents of 

 this memoir the following extracts may be regarded as a summary. 



" I have supposed that a number of material molecules are plunged 

 into a boundless aether, and that these molecules and the atoms of the 

 aither are subject to the actions of the forces required by the theory 

 of iEpinus, and then endeavoured to ascertain the conditions of 

 equilibrium of the aether and the molecules. Considering the aether 

 as a continuous mass, and the molecules as isolated bodies, I found 

 that if the latter be spherical, they are surrounded by an atmosphere, 

 the density of which decreases according to a function of the distance 



