safety under the severe strains to which they are subjected, arose from the excess of carbon and the deficiency of manganese in the natural alloy spiegeleisen.

I may here state that, very soon after commencing the manufacture of steel at my Sheffield works, this difficulty about mild steel plates was strongly felt when using British coke-made iron. I attained complete success with Swedish charcoal iron, and thus could make tool steel and gun steel as good as, or better than, any in the market. On these steels there was a large profit, and the cost of the material was not important. But when the steel had to be sold in competition with iron plates, it was necessary to use cheaper pig iron, and it was with this iron that the difficulties arose. However, I found that another of Nature's compounds, wholly differing from spathose ore, or white carbonate of iron, from which spiegeleisen is obtained, existed in large quantities in New Jersey, in the United States. The mineral referred to is a ferriferous oxide of zinc, and on its discovery it was given the name "Franklinite," in honour of Dr. Franklin. When the zinc is driven off, in the form of vapour, there results an alloy of iron and manganese, usually containing from 11 per cent. to 11 1/2 per cent. of manganese, which is far better adapted for the deoxydation of mild steel than spiegeleisen, containing only 8 per cent. of that metal. Consequently, "Franklinite" was much used at my works in Sheffield, pending my introduction of ferro-manganese into the trade. This, unfortunately, from a variety of circumstances, was delayed until 1862, when I induced a Glasgow firm to go into the manufacture of ferro-manganese, both for our own use at Sheffield, and for the benefit of my licensees. The subjoined extract will show how valuable this ferro-manganese was, more especially for plate-making, and how much the Bessemer mild steel plates of that early date suffered in reputation by the undue introduction of carbon into the metal from the use of spiegeleisen, so rich in carbon, and so poor in manganese. I quote one of the highest living² authorities, a gentleman who enjoys both an American and a European reputation as an iron and steel manufacturer and metallurgist. I refer to Mr. Abram S. Hewitt, the United States Commissioner to the Universal Exposition at Paris in 1867, who, in his able report to the American Government, commented on the Bessemer process and its application to the manufacture of plates as follows :-

The application of the Bessemer process to the production of plates either for boilers or for ships, girders, etc., is one of the most important that could be made. Nevertheless the amount of metal used for this purpose in England falls much below that employed for other purposes. This is due to a certain amount of distrust of steel plate, doubt as to its reliability under varying strains of tension and compression, its capability of being punched and sheared without injury to itself, and of its action under the influence of heat and water as in the fire-box of a boiler. In other countries, as for example Austria, as will be shown when we come to speak of the manufacture as carried on in that country, this has not been the case, and large quantities of plates have been produced and successfully applied to a variety of uses.

The secret of the distrust in regard to Bessemer plates in England is that in nearly all cases the percentage of carbon contained in the metal has been too large. The spiegeleisen used in England is not particularly rich in manganese -- seldom exceeding nine per cent. of that element, while it generally contains from four to four and a half per cent. of carbon. It is difficult, therefore, with such materials to deoxygenate the metal sufficiently without introducing also a considerable percentage of carbon. About 0.4 per cent. of the latter is as large an amount as is proper for plates which are to resist severe strains, and though a greater proportion adds materially to the tensile strength of the m