82 ANNUAL OP SCIENTIFIC DISCOVERY. 



In BirminQ-ham it is made from the folio win of mixture : — 



cwts. qrs. lbs. 



French sand, 6 — — 



Carbonate of soda, 1 3 7 



Lime 2 7 



Nitrate of soda, 1 



Arsonious acid, 3 



m 



The be?t qualities of this glass are at present produced in the 

 Siemens furnace. 



CUTTING GLASS WITH STEEL. THE MAGIC DIAMOND. 



The cuttino^ of f]^lass with steel has been demonstrated to be 

 possible, j)rovided its point is ground into the form of a common 

 glazier's diamond. But while hard steel of this form will cut 

 glass, it is dillicult to bring a steel point to the required shape, 

 and it also soon wears out and becomes worthless, until reground. 

 Many efforts have been made to make a tool of steel that would 

 compete at least approximately with the real diamond for this 

 purpose. It has been discovered that a small cylindrical point of 

 steel, when made to rotate upon glass in such a manner that its 

 longitudinal axis shall make an ancfle of 45 deofrees with the sur- 

 face of the glass, approaches in effect so nearly to that of the real 

 diamond that it is a very cheap and effective substitute. 



HEAVY MODERN MACHINERY. 



A mass of metal of a ton weight was unknown before the 

 Christian era. Now those in cast iron up to 150 tons, in wrought 

 iron to 40 tons, and in steel or bronze to 25 tons, are made in any 

 desired form, and turned or bored with the most perfect accuracy. 

 Two years ago I saw the largest lathe in England, which swings 

 22 feet, and will take in a shaft 45 feet long. Six months ago I 

 saw one in this country which swings 30 feet, and will take in a 

 shaft of 50 feet. There are j)lan('rs which will plane iron 50 feet 

 in length; others of 18 feet in width; others of 14 feet in height, 

 takins: off" metal shavini^s of two and a half inches in width and a 

 quarter thick. — W. J. McAlpine. 



NEWEST COLORING MATTERS. 



A lecture has been given by !Mr. W. II. Perkin, at the Boyal 

 Institution, "On the Kewest Coloring ^Matters." Among the 

 many interesting fiicts then put forward was the discovery of a 

 beautiful ])lue color, by a (Jerman chemist, on treating rosaline 

 with sulphuric acid. Unfortunately, it was not a " fast color." 

 A dyer made many trials therewith, in the hope of turning it to 

 account, but all in vain. He happeiKnl to mention his diiliculty 

 to a photographer, who, knowing that hypostilphite of sodium 



I 



