Show has made quartz fusible it Is not so long ago that the textbooks on minerals used to describe quartz as infusible the electric furnace has made this an ail error and now some manufacturers of chemical devices devote special catalogues cataloguer catal to apparatus made of this substance there are two grades on the market the kind made from rock crystal and looking almost precisely isely like ordinary glass and the cheaper translucent variety made of common silica and sometimes called in the trade electro quartz both kinds are valuable in the chemical labora laboratory because vessels made of elther either resist all acids but hydrofluoric and cannot be cracked by the change of temperature however violent quartz is useful also for its insulating properties which are nearly perfect |