28 ANNUAL OF SCIENTIFIC DISCOVERT. 



PROCESS FOR CASTING STEEL UNDER HIGH PRESSURE. 



The following is an extract from A. Galy-Cayalat's patent for 

 casting steel under high pressure : — 



"It is well known that cast steel run into moulds is subject to 

 blister, and is otherwise porous, which defect reduces considerably 

 its toughness. In order to give this metal its requisite tenacity, 

 it is subsequently reheated and then rolled and hammered. As 

 many articles, such as cannon, cannot be treated in this manner, 

 I have devised to submit them to a high pressure while in a liquid 

 state inclosed in their sand moulds maintained in iron flasks. For 

 this purpose, immediately after running a cannon, I cover hermet- 

 ically the head by a metallic cap, by means of bolts or other devi- 

 ces attached to the flask. This cap is fitted in its centre with a 

 vertical pipe, and provided with a cock at its lower extremity, 

 while its upper extremity is closed by a washer pressed with a 

 bolt in such a manner as to act as a safety valve. Before attach- 

 ing the cap at, supposing an inch from, the surface of the liquid 

 metal, I introduce in the vertical pipe, and between the cock 

 and the washer a charge of about one quarter of an ounce of 

 gunpowder, in the proportion of 80 parts of saltpetre and 20 

 of charcoal, with no sulphur. On opening the cock this powder 

 falls on the metal, ignites, and engenders about one third of a 

 cubic foot of gas at 1,400° Cent. These gases exert on the liquid 

 metal a pressure which is transmitted through the entire mass, 

 thereby condensing the same and expelling the blisters. The 

 eff'ect thus produced is equivalent to the pressure of a head of 

 liquid metal 90 feet high, admitting that the capacity between 

 the cap and the surface of the metal contains 30 cubic inches. 

 By making the flasks sufficiently strong the charges of powder 

 may be varied, so as to'produce by its ignition a uniform and 

 general pressure, which is preferable to the partial, irregular, and 

 momentary action of a hammer." 



CHROME IRON AND STEEL. 



Iron and Cliromium and Chro7nium Steel. — Iron and chromium 

 may be alloyed in every proportion by heating the mixed oxides 

 strongly under addition of charcoal powder, to eftect reduction. 

 Fremy formed an alloy by heating in a blast furnace oxide of 

 chromium and metallic iron, thereby obtaining a product resem- 

 bling cast iron. These alloys are generally hard, brittle, with a 

 bright fracture, and crystalline in structure. When they contain 

 a large percentage of chromium they crystallize in long needles. 

 They are also less fusible, not as magnetic, nor so easily attacked 

 by acids as iron. The alloy of 95 per cent, iron and 5 per cent, 

 chromium is stated to be hard, splitting under tlie hammer and 

 scratching glass. The fracture is very bright, with crystalline 

 plates extending across the fractured surface. The alloy of 75.2 

 per cent, iron is readily reduced to powder ; its fracture is tin white, 



