and a high vacuum was produced, the ebullition set up by the rapid escape of gas caused the steel to boil over the top of the crucible, and occupy the lower part of the chamber, as shown in the engraving.

Many experiments were made with this simple apparatus, and they convinced me at the time that it was far preferable to blow the metal only to the condition of steel, using the recarburising process to as small an extent as possible. Thus it happened that in my early patent of October l7th, 1855, I described the recarburising process in the words which I reproduce from my printed specification, which dates more than one year prior to Mr. Mushet's patents.

During the decarbonizing process, the state of the metal may be tested by dipping out a sample with a small ladle, as practised in refining copper; if too much carbon is retained, the pipe G may be again introduced for a short time, or a small quantity of scrap iron may be put into it; but if too much carbon has been driven off, an addition may be made of some melted iron from the finery or cupola furnace: a little experience will, however, enable the workman to regulate his process so as to produce the different qualities of steel which he may require.

This quotation shows that, from the earliest date, I fully understood and appreciated the facility which molten carburet of iron gave for regulating the state of carburation of the converted metal; and if I used any kind of manganese pig iron for converting into steel, as I had a perfect right to do, the addition of some of this molten iron "from the cupola furnace" to my converted metal, would of necessity involve the recarburising, by the use of a "triple compound of iron, carbon, and manganese."

Now the particular manganese pig iron, called in Styria spiegeleisen, the use of which Mr. Mushet claimed by his patent, may in round numbers be fairly stated to consist of 4 per cent. carbon, 8 per cent. manganese, 2 per cent. of some half a dozen other elements, and 86 per cent. of iron. These proportions are by no means well adapted for the deoxydation of mild steel, and it is impossible to use such a metal when soft decarburised iron is desired, as steel, and not malleable iron, would be produced.

I have before stated, that in my earliest experiments the quantity of oxygen taken up by the metal was but small, if the process was stopped when the desired quality of steel was arrived at. But if I continued the blowing process until soft iron was produced I had a double disadvantage: I burnt and destroyed -- as I have already stated from 2 to 3 per cent. more of the iron than was lost when making steel, and I immensely increased the quantity of oxygen absorbed. It was this fact that induced me to persevere in decarburising only to the extent necessary to make steel of the precise quality desired; and where this system has been pursued in Sweden and in Austria, it has proved commercially a great success.

It will at once be seen how ill-adapted are the proportions of carbon, manganese, and iron, in spiegeleisen, because enough of the per cent. of manganese present cannot be put into the converter to deoxydise the malleable iron, without introducing at the same time so much of the 4 per cent. of carbon present as would make the whole of the malleable iron treated, into cast steel. For this reason the very soft or mild quality of steel required for ship and boiler-plates should be recarburised with an alloy of something like the following proportions: 60 per cent. of manganese, 4 of carbon, and 36 of iron.

Now, if Mr. Mushet had invented a new triple compound of iron, carbon, and manganese, in somewhat about the proportions indicated, and had shown a cheap and ready way of producing it on a commercial scale, he would have been entitled to a patent for his mode of producing such an alloy, and also for the use of such an artificial compound in any other process to which it might be applicable. But it was not new to improve steel by alloying it with manganese: a method long before known to, and daily practised by, hundreds of workmen in the steel trade.

This patent of Mr. Mushet, claiming the sole use of manganiferous pig iron, had simply the effect of calling the attention of steel-makers to a makeshift alloy, and thus diverted for some years my attention, and doubtless that of many other persons, from the pursuit of a ready means of producing such an alloy of manganese as would be better suited for the purposes for which spiegeleisen had been employed. All the difficulties in making boiler and ships' plates of the degree of mildness necessary to ensure their