74 Progress of Invention. 



PROGKESS OP INVENTION. 



Economic Production op Formic Ether, on the Large Scale. — 

 The peculiar odour of the peach, possessed by this compound, has 

 recently given to it an importance that renders any simplification 

 or diminution of expense during its manufacture a matter of inte- 

 rest. It may be very conveniently made by placing a mixture con- 

 taining twenty-nine parts, by weight, peroxide of manganese, and 

 nine parts starch in an alembic, and sprinkling it with a mixture 

 formed with twenty-eight parts sulphuric acid, five parts water, and 

 fifteen parts alcohol, and, after agitation, closing the alembic. 

 Distillation takes place generally without the application of heat ; 

 the products being, first, alcohol, then nearly pure formic ether, 

 and, finally, formic acid. Before sprinkling with the alcoholic 

 mixture, the latter should be cooled, or the action may be far too 

 energetic. 



Improvement in the Manufacture of Steel. — In the old mode 

 of forming steel all the carbon is removed from the cast iron, malle- 

 able iron being formed ; and steel is made from this malleable iron 

 by the addition of the proper amount of carbon. By the, Bessemer 

 process only enough carbon is removed from the cast iron to change 

 it to steel ; and the carbon is removed by the introduction of an 

 abundance of atmospheric air into the cast iron in a state of fusion. 

 The oxygen of the air burns the carbon. It might be supposed that 

 any substance capable of affording oxygen, introduced into the fused 

 cast iron, would answer instead of atmospheric air ; and therefore 

 the use of substances, such as nitrate of soda, etc., capable of fur- 

 nishing large quantities of oxygen, was very soon attempted. But 

 it was found that the very property possessed by these compounds of 

 affording oxygen, caused them to rapidly destroy the converter — a 

 vessel in which the change from cast iron to steel was effected. 

 Not only was the carbon of cast iron, but the metal of which the 

 converter was formed, burned. This was, of course, fatal to the em- 

 ployment of these salts as a source of oxygen. The difficulty was, 

 however, not insuperable, and it has since been overcome. The con- 

 verter is lined with a refractory material, and the nitrate is placed 

 in pockets formed in this material. The cast iron is brought in 

 contact with the nitrate, by means of a rapid rotation imparted to 

 the converter : and the centrifugal force thus generated throws the 

 fused cast iron into violent collision, and thei-efore complete con- 

 tact with, the salt. 



New Breech-loading Gun. — A safe and very simple breech- 

 loading gun has been recently invented in France. The gases 

 generated by the explosion are prevented from escaping at the 

 breech by the application of the principle used by Bramah to render 

 the pistons of hydraulic presses water-tight, however great the 

 pressure. Attached to the screw that forms the breech of the gun, 

 is a thimble of soft copper which protrudes into the barrel, and when 

 the gun is tired its sides are expanded by the gases in all directions, 

 so that no gas or vapour can escape between it and the barrel. There 





