79 - Jean-Charles SCHEMMANN (1801 - ) [1]

In 1862 Johann Carl SCHEMMANN, négociant in Hamburg, filed patent applications in Germany, France, England and Italy for his invention: “Verfahren zur Darstellung von Gussstahl und Gerbstahl aus Rohstahleisen”. [2]

On 1 June 1864 SCHEMMANN applied for a brevet d’importation in Luxembourg, presumably based on his corresponding German patent. 

The French title given to the invention was:

Procédé nouveau et particulier pour transformer la fonte de fer en acier fondu

In the introduction to the corresponding English patent the inventor explains:

My Invention consists in operating upon iron in the puddling furnace, and subsequently in a manner hereafter described. 

When iron in the puddling furnace reaches that point where the escape of carbonic oxide ceases, the melted iron assumes a granular state. In this state the melted iron has lost its properties as pig or raw iron, the greater portion of the carbon having escaped, and part of the other heterogeneous substances commonly found in iron having been volatilised or mixed with the slag, the iron in this state is no longer pig iron, but has become purified iron containing a certain quantity of carbon, and in this combination it is hard steel, richly saturated with carbon. 

On the metal being worked through still further, under suitable regulation of the furnace, every conversion beyond this granular state causes a decrease of carbon in the metal, until it will finally become iron. Between each grade of further decarbonisation the mass has become steel, containing a different amount of carbon, and is of a different degree of hardness, say, from the maximum to the minimum. 

Up to the present, this fact has not been sufficiently acknowledged, or rather, no attention has been paid to discover a process in order to obtain steel at the various stages of the decarbonisation. 

Now, I commence to operate upon the iron as soon as it assumes the granular state in the puddling furnace. On the mass reaching that granular state which I consider fit for the particular kind of steel I desire to produce, I at once shut off the draught in the furnace, open the door, and take the whole mass out as quickly as possible, and throw it into cold water, by which means the steel hardens, and gets rid of the slag and cinder.

Experts Ch. Fr. MERSCH and F. REUTER examined the invention on behalf of the Chambre de commerce. Their lengthy report concludes as follows:

Toute la partie de ce procédé, à partir du moment où les matières plus ou moins cohérentes sont retirées du four à puddler, jusqu'à la confection de lopins, ou du changement de creusets, pour refondre la poudre, est parfaitement nouvelle, et paraît être de l'invention du demandeur du brevet.

Les experts soussignés nommés par la Chambre de commerce, à l'effet d'examiner la demande du sieur J. G. Schemmann, sont donc d'avis qu’il y a lieu d'accorder le brevet demandé.

The patent was granted on 1 October 1864.


[1] FamilySearch database

[2] FR patent No 55,236; GB patent No 2,335/1862; IT patent  n° 355/1862