POLTTECHNIC ASSOCIATION PROCEEDINGS. 1009 



A discussion followed the reading of these items. That on 

 " New Alloys of Lead and Tin " drew forth Dr. Vanderweyde, 

 who described the method of making the tin-foil, now in common 

 use, by rolling a thin plate of lead between two thinner plates of 

 block-tin, the resulting product being, in reality, lead-foil covered 

 with tin. He mentioned instances of lead poisoning on the part 

 of tobacco chewers, who had chewed with the tobacco the foil 

 employed to enwrap the same. It was also mentioned that the 

 gilt wire used in the manufacture of epaulets, etc., is made in a 

 manner somewhat similar to that of making foil. A coarse wire 

 is first heavily gilded, and afterwards drawn down to the requisite 

 degree of fineness. 



Dr. W. Rowell stated that the method now used for tinning the 

 internal surfaces of electrotype plates, as required previous to 

 backing them with the ordinary filling of type metal, is to place 

 tin-foil thereon, which, being melted readily, adheres, thus securing 

 the object sought. After some further discussion of other items, 

 new inventions were exhibited. 



NEW METHOD OF SETTING WINDOW GLASS. 



Mr. J. R. Eddowes, of Philadelphia, exhibited specimen of win- 

 dows, in which the glass was set and secured in the sash by his new 

 method. He remarked that putty is so generally used for confining 

 and securing glass in windows, that it would almost seem super- 

 fluous to advocate the employment of any substitute, yet it is well 

 known that this means of confining glass in place has its disadvan 

 tages, inasmuch as the action of the elements will in time cause the 

 putty to become loosened, and its renewal is then necessary. If 

 at any time before this detriment to the fastening* takes place, a 

 pane of glass becomes injured or broken, and it is deemed advisable 

 to remove it, it is sometimes difficult so to do, and much injury may 

 result to the sash in which the pane was held. 



The model shows the pane of glass inserted in a suitable rabbet 

 in the sash, and fitted at each side of the inner circumference of 

 the sash or frame, and over the edges of the glass is a clamping 

 plate, and furnished with flat lugs, through which screws are 

 inserted for the purpose of holding this clamp to the sash. Placed 

 between the clamping-plates and the sash is a packing, which may 

 be made of a tube of rubber or any similar packing material, 

 which, being snugly compressed between the plate and the glass, 

 eff'ectually holds the latter in place, and from its yielding nature 



flNST.] 64 ■ 



