PoLYTECNic Association Proceedings. 709 



in Europe. The process was never carried into practica. operation 

 for commercial purposes in this country; however, a large company- 

 was formed in France, more than ten years ago, for making steel 

 under the Ucliatius patents, but it failed to produce steel of uniform 

 quality. The cause of its faikire is now known to be the employ- 

 ment of improper ores. In Sweden this kind of steel has been 

 made with great success, by mixing the very pure and rich mag- 

 netic ores of the Bisberg mines with granulated pig u'on made from 

 the same ore, and adding a little manganese or manganese ore. 

 This steel is remarkable for its tenacity and uniformity of grain. 

 It is used exclusively b}^ the Roj^al Mint at Stockholm for dies of 

 coining presses, polished rolls and other similar articles requiring 

 great strength, closeness and regularity of grain. 



Prof. Vanderweyde remarked that fen-o-cyanide of potassium 

 applied to iron, made a coating like steel, but it is so thin that it 

 soon wears off on a tool which is often ground to shai*pen it. He 

 had made magnets in this way, but they were not of much account, 

 as the steel did not penetrate far into the iron. 



THE COLORS OF SOAP BUBBLES. 



At the late meeting of the British Association for the Advance- 

 ment of Science, Sir David Brewster read a paper on this subject, 

 from which it appears that he had been led to make some new 

 investigations as to the cause of colors of soap bubbles, after he 

 had repeated the beautiful experiments of Prof Plateau " On the 

 Equilibrinm of a Liquid Mass without Gravity." In these cases 

 the colors of soap bubbles were presented to him upon soap films, 

 plane, convex and concave; but the changes of form which they 

 underwent, and their motions upon the film itself, were incompati- 

 ble with the common theory of their formation. After describing 

 various phenomena emitted by the ordinary soap bubble, and also 

 with the bubble having its film toughened by a mixture of glyce- 

 rine. Sir David remarked that his experiments were sufficient to 

 establish the almost incredible truth that the colors of the soap 

 bubble are not produced by the thickness of the film itself, but 

 b}'^ the secretion from it of a new substance flowing over the film 

 and expanding, under the influence of gravity and molecular forces, 

 into colored groups of various shapes and returning spontaneously, 

 when not returned forcibly, into the parent films. 



At the conclusion of the paper. Sir William Thomson remarked 

 that the mechanical questions involved in the seemingly simple 



