Chemical Science. 205 



decomposed, muriatic acid is formed, and the soda produced 

 unites with the silica to make the necessary glaze. As to the 

 oxide of iron, its history will be best understood by an experi- 

 ment or two. If a mixture of salt, oxide of iron, and silica, 

 be heated to redness in a tube, and water in vapour be passed 

 over it, nmch muriatic acid is formed, but very little chloride of 

 iron, and crystallized oxide of iron will be found in the mass : 

 but if muriatic acid be brought in contact with ignited oxide of 

 iron, water and chloride of iron are formed, and sublime 3 if the 

 chloride of iron come in contact with more water, muriatic acid 

 is first developed, then chloride of iron, and a residue of crystal- 

 lized oxide of iron remains. The formation of chloride of iron 

 by the action of muriatic acid upon oxide of iron appears, there- 

 fore, to depend upon the proportion of water present. M. Mit- 

 scherlich applies these experiments and principles in explanation 

 of the manner in which volcanic crystaUized oxide of iron is 

 formed — all the conditions necessary, according to the above view, 

 being present in those cases, where heretofore it had been sup- 

 posed the oxide of iron, as such, had been actually sublimed. 

 — Annalen der Phys'ik. — Bull. Univ. B. xix. 245. 



10. M. Becquerel on Metallic Sulphur ets, Iodides and Bromides. — 

 The researches of M. Becquerel into the nature of minutely 

 exciting causes of electrical action, and the effects of electricities 

 of feeble intensity, are well known, both for the ingenuity and 

 the industry with which they have been carried on. Lately, he 

 has been led to conceive, that many of the minerals in the rocks 

 forming the surface of our globe may have been the result of 

 the influence of feeble electric powers acting upon ordinary matter. 

 He puts a question thus : " Have the mineral substances in veins 

 been originally dissolved in a liquid, which, by slow dissipation, 

 has allowed the molecules to come together, under a crystalline 

 arrangement? or, have they resulted from the slow decomposition 

 of certain combinations but little soluble into which they entered, 

 as constituent parts ?" and believes that the facts he afterwards 

 quotes throw light upon it. 



The apparatus used consisted of two small tubes, a and b, 

 open at both extremities, placed upright, side by side, and filled 

 in the lower part with very fine clay, slightly moistened with a 

 liquid capalile of conducting electricity. Such liquids are to be 

 poured into the upper parts of the two tubes, as are competent, 

 under the circumstances, of acting upon the metal experimented 

 with. The metal may be a single plate, bent so as to be im- 

 mersed in the fluid of both tubes, and connect them together ; or 

 it may be a compound-metallic communication. The two tubes 

 are placed in a third, large enough for the purpose, which is to 

 be partly filled with a fluid, intended to complete the electric 

 communication through the apparatus. Thus arranged, the clay 

 retards the mixture of the fluid in the two smaller tubes, and 



