470 Miscellaneous Intelligence, 



then the distance at which the change seemed to take place would 

 have been the spot for some interesting experiments. — Ed. 



2. Fissures of Glass. — These fissures are distinguished by M. 

 Fischer into four kinds. The first are such, that the liquid con- 

 tained in the broken vessel escapes through them into the air. The 

 second are such as retain the liquid, unless the vessel be immersed 

 in water, or a similar fluid, and then the level of the two portions 

 of fluid tend to approach each other. The third are not permeable 

 unless the fluids on opposite sides have a chemical action on each 

 other J whilst that action continues, the fissure is permeable, but 

 being over, there is no longer a tendency to equality of level. This 

 is also the effect produced by the membrane of the bladder. 

 The fourth kind are so fine that no fluid passes, except in a single 

 case. If a solution of nitrate of silver be put into a glass tube 

 with such a fissure, the latter plunged into water, and then the 

 liquids connected by a voltaic circle, consisting of a platina wire 

 and one of copper or zinc, so that the platina shall be in the solu- 

 tion of silver, and the other wire in the water, in about twenty- 

 four or forty-eight hours crystals of silver will be found on the 

 platina wire, and nitrate of zinc or of copper in the water. If no 

 voltaic circuit be used, no salt of silver will be found in the water 

 even after many days. Salts of lead, tin, and copper will not pro- 

 duce this curious effect. — Annalm der Phys. 1827, p. 481. 



3. Change of Crystalline State in a solid Body. — " It was in the sul- 

 phate of magnesia that I first remarked the change, in form, of a 

 solid body, or, more accurately, the change in the position of its 

 atoms, without the assumption of the liquid state. If this salt or the 

 sulphate of zinc be slowly heated in alcohol, and gradually raised 

 to ebullition, the crystals will lose their transparency by degrees, 

 and, when broken, they will be found to be formed of a great 

 number of new crystals, entirely different in their form to those of 

 the salt employed." — Mitscherlich, Annates de Chimie, xxxvii. 206. 



This is a case of internal motion to be added to those already 

 known of basalt, arsenious acid, barley-sugar, sulphur, &c. &c. 



4. Hardening cf Steel by a current of compressed Air. — From the 

 observation of travellers, that the manufacture of Damascus blades 

 was carried on only during the time when north winds occurred, 

 M. Anozoff made experiments on the hardening of steel instru- 

 ments by putting them, when heated, into a powerful current of 

 air, instead of quenching them in water. From the experiments 

 already made, he expects ultimate success. He finds that, for 

 very sharp-edged instruments, this method is much better than 

 the ordinary one ; that the colder the air and the more rapid its 

 stream, the greater is the eflfect. The effect varies with the thick- 

 ness of the mass to be hardened. The method succeeds well with 

 case-hardened goods. — Bull. Univ, E. ix. 134. 



