TECHNOLOGY. 403 



trials by stripping stress. Second, that the cold -punched 

 nuts exhibited a strength never attained by the hot-pressed 

 nuts, but that such variations in the strength of both styles 

 occurred as to have caused the hot-pressed nuts to equal, 

 and occasionally to excel, in strength the weakest specimens 

 of cold-punched nuts." 



IRIDESCENT GLASS. 



Some interesting results of experiments upon the artificial 

 production of the iridescent glass of the ancients, so highly 

 prized by antiquarians, have been reported by two French 

 chemists, MM. Fremy and Clemandot. These investigators 

 ascertained by observation that glass, when subjected to con- 

 ditions which determine its gradual decomposition, becomes 

 covered with slender laminae which present the remarkable 

 phenomenon of irisation. They have succeeded, according to 

 account, in producing this irisation on glass so that it shall 

 present the peculiar appearance of mother-of-pearl, by sub- 

 mitting it, under the influence of heat and pressure, to the 

 action of water containing 15 per cent, of hydrochloric acid. 

 Only certain kinds of glass, however, are suited for this treat- 

 ment, and the conditions of composition as well as those of 

 annealing affect the result. 



It is not improbable that this observation may be the ini- 

 tial step to the restoration of "a lost art" or the establish- 

 ment of a new one. The products of this new manufacture 

 ornamental vases, cups, bowls, etc. which appear to have 

 already been placed upon the market abroad in considerable 

 quantity, though very beautiful, are said to be as yet much 

 inferior to the Assyrian or Egyptian iridescent glass, in the 

 production of which time is held to be an important factor. 



MISCELLANEOUS. 



Some attention was attracted among iron-workers by the 

 announcement of the discovery, by Professor Barff, of a meth- 

 od by which iron may be effectually prevented from rusting, 

 and, " however much exposed to the weather or corrosive va- 

 pors or liquids, rendered practically indestructible and ever- 

 lasting." The process in question consists, substantially, in 

 subjecting the iron to the action of superheated steam, where- 

 by it acquires a thin but firmly adherent coating of magnetic 



