180 ANNUAL OF SCIENTIFIC DISCOVERY. 



constituent parts, but as a particular state of iron produced by the 

 union of this metal with bodies the nature of which is variable ; and 

 it is from this point of view that, after defining steel, independently 

 of all scientific considerations, as an iron which is hardened by tem- 

 pering, I would discriminate steels as follows : 



1. Steels formed by iron and carbon ; 



2. Steels formed by iron, carbon, and a third body ; 



3. Steels formed by iron and some other body, which is not carbon ; 

 or uncarbouized steels. 



Professor Fairbairn, in alluding to the discoveries of M. Frcmy, in 

 his address as President of the British Association (1861), uses the 

 following language : 



" There is little doubt that in a few years these discoveries will 

 enable Sheffield manufacturers to replace their present uncertain, 

 cumbrous, and expensive process, by a method at once simple and 

 inexpensive, and so completely under control as to admit of any re- 

 quired degree of conversion being obtained with absolute certainty. 

 Mr. Grace Calvert also has proved that cast iron contains nitrogen, 

 and has shown that it is a definite compound of carbon and iron 

 mixed with various proportions of metallic iron, according to its 

 nature." 



NEW COMPOUND OF MANGANESE. 



Various oxides of manganese have been produced artificially by M. 

 Kuhlmann, by processes described by him in a paper submitted to the 

 French Academy, and printed in the Comptes Rendus. Among these 

 artificial products is manganate of lime, a salt remarkable for its de- 

 colorizing and disinfecting properties. If this can be economically 

 prepared, a valuable reagent will be abundantly placed at our dis- 

 posal. 



CUEIOUS EXAMPLE OF EXPLOSIVE FORCE. 



Mr. Robert Mushett, in a communication to the London Engineer, 

 states that by pouring melted pig iron into decarbonized metal, a 

 fearful explosion ensues. " This rash act," he says, " of pouring cast 

 iron into decarbonized metal while air is being forced through it was 

 only once committed, and fortunately only a few hundred pounds of 

 metal were being operated upon. But the whole of the metal was 

 projected, as from a gun, into the air, carrying away the top of the 

 furnace, setting the roof of the lofty cast-house on fire, scalding some 

 of the workmen, and nearly terminating the mortal career of Mr. 

 Thomas Brown, who was superintending the operation. It is many 

 degrees more dangerous than setting fire to a magazine of gun- 

 powder." 



SILVERING GLASS AND PORCELAIN. 



Mr. E. R. H. linger, in a letter to the editor of the Chemical Neivs, 

 states: "In making various experiments the other day with nitrate 

 of silver, I happened to add to a small quantity of a strong solution 

 of that compound an equally small quantity of a thick alcoholic solu- 

 tion of tannin. The quantity, though small, was exposed with a 

 comparatively large surface to the atmosphere, by making use of a 

 flat-bottomed evaporating dish. 



