Faraday to Charles-Gaspard De La Rive   26 June 1820

Royal Institution London | June 26th 1820.

My Dear Sir

Not long since I troubled you with a letter in which I said I would shortly send you an account of some experiments on steel made by Mr. Stodart & myself. A paper will appear in the next No. of our Journal¹ which will contain all we have as yet ascertained on the subject and as the results seem to me to be interesting I hope you will not be sorry that I keep my promise by mentioning the principal of them to you. In the small way in which only we have as yet worked they are good and I hope that no failure will occur when the processes are transferred to the Manufactory.

It is possible you may have observed an analysis of Wootz or the Indian steel published in one of our Journals some time since²[.] I could at that time find nothing in the steel besides the Iron & carbon but a small portion of the earths or as I presume their metallic bases. On the strength of this analysis we endeavoured to demonstrate the particular nature of Wootz synthetically by combining steel with these metallic bases and we succeeded in getting alloys which when worked were declared by Mr. Stodart to be equal in all qualities to the best Bombay Wootz. This corroboration of the nature of Wootz received still stronger confirmation from the property possessed by the Alloys in common with Wootz namely their power of yielding damasked surfaces by the action of acids. When Wootz is fused & forged it still retains so much of the crystalline structure as to exhibit when acted on by very weak sulphuric acid for some time a beautiful damasked surface. This we have never yet seen produced by pure steel but it is produced in our imitation of wootz or alloys of steel with the metal of Alumine[.]

I must not forget to tell you how we formed our alloys. Many attempts failed the following method succeeds. Fuse iron in small pieces with charcoal powder. If the button produced is malleable break it up & re-fuse it with more charcoal. In this way a carburet of Iron will be formed which has its place between steel & plumbago. It is fusible when broken has a dark grey colour and is very highly crystalline[.] It is so brittle that small pieces of it may be rubbed to powder in a mortar. Some of this powdered carburet was then mixed with pure alumine & the whole strongly heated. A portion of the alumine was reduced by the carbon of the carburet and a compound of Iron Aluminium & carbon was obtained[.] Then English cast steel being mixed with about 10 per cent of this alloy the whole was fused and our artificial wootz obtained.

I presume that the properties of Wootz are so well known to you that I need not stop to say what are the supposed improvements in steel when it is converted into Wootz.

Whilst making the carburet above mentioned we also succeeded in forming plumbago but I am afraid this artificial production of it will not be very useful in its application[.] If Iron be heated highly and long enough in contact with charcoal plumbago is always formed. I have some buttons of metal here weighing 2 or 3 ozs that appear to be solid plumbago[.] The appearance however is deceitful for it is only on the surface & to the depth perhaps of 1/40 of an inch that the plumbago has been formed[.] The internal part is composed of the crystalline carburet before mentioned[.] What is plumbago is very good and marks excellently well and though we have never yet been able to fuse powdered plumbago into a mass yet I think that if it were required to form it in a compact state to work up into pencils it might be done by embedding plates of Iron about the 1/20 of an inch thick in charcoal & heating intensely for a long time[.] This we have not yet had time to try but intend to do so.

You will readily suppose that during nearly 2 years that we have been at work on this subject a great deal of useless matter except as furnishing experience has accumulated. All this you will rather wish away so that I shall pass over unimportant alloys to write of those which promise good results[.]

Perhaps the very best alloy we have yet made is that with Rhodium[.] Dr. Wollaston furnished us with the metal so that you will have no doubts of its purity and identity. One & a half per cent of it was added to steel & the button worked. It was very malleable but much harder than common steel & made excellent instruments[.] In tempering the instruments they required to be heated full 70°F. higher than is necessary for the best cast steel and from this we hope it will possess greater degrees of hardness & toughness. Razors made from the alloy cut admirably.

Next to the alloy of Rhodium comes that of silver about which there are many curious circumstances. Silver refuses to combine with steel except in very small proportions and this want of affinity is much greater when the metals are cold than when hot. If for instance 100 steel & 1 silver be fused together cooled hammered &c. &c. and then laid in a weak sulphuric acid for 10 or 12 hours its structure will be developed & it will be found to be a congeries of fibres of steel & silver the one distinct from the other but intimately mixed in every part[.] Now the perfect dispersion of the silver throughout all parts proves that it has been taken up by the steel whilst in fusion but its separate state of existence shews that it has been rejected from the alloy as it solidified[.] Indeed this refusal of the silver by the steel as it cools is so remarkable that if the hot alloy be observed globules of silver may be seen extruded from the surface as the temperature falls.

But however; we went on diminishing the quantity of silver as long as its separate existence could be observed in the alloys and when we arrived to a 1/500 part we found that the whole remained in combination with the steel. This Alloy was excellent all the cutting instruments made of it were of the best quality & the metal worked without crack or flaw and with remarkable toughness & malleability under the hammer.

The Alloy of steel and platinum is not so marked by an acquir[ed] superiority as the two I have already mentioned and yet platinum in quantities from 1 to 3 per cent does seem to be of advantage to steel but we are now continuing this subject. The powerful affinity with which the platinum combines with the metals generally, meets with no exception when tried with Iron or steel; they unite in all the proportions we have tried from 1 platinum to 100 steel up to 90 platinum to 20 steel[.] We expect a good deal from some of these higher compounds[.]

I think the affinities of platinum & silver for steel are worth comparing together[.] Though they stand almost together in an electrical arrangement of the metals and both of them very far from Iron or steel still they do not exhibit attractions for steel at all comparable[.] Platinum will combine in any proportion apparently with steel or Iron and at temperatures so low that the two metals may be welded together at heats barely sufficient to weld Iron whereas it is with difficulty that a 1/500 part of silver is made in any way to combine with steel[.]

I hope my Dear Sir I have not tired you yet for I am now going to begin writing across but I will promise not to detain you very much longer either by excuses or details - We have been induced by the popular idea that meteoric Iron would not rust to try the effect of Nickel on Steel & Iron[.] We made alloys of Iron & nickel varying the latter metal from 3 to 10 per cent and we thought we found that they were not quite so oxidable as Iron alone when exposed with it in greenhouses & in our laboratory[.] But Nickel alloyd with steel gave us no hopes[.] It appeared more oxidable than simple steel and this fault was not compensated for by any other good quality. So for the present we have dismissed that metal from our experiments though I expect as we go on we shall find many occasions to resume thoughts and intentions which we may have laid down[.]

Mr Children has obliged us with an accurate analysis of the Siberian Meteoric Iron and he finds it to contain a very large proportion of nickel[.] In the mean of three experiments it amounts to 8.96 per cent.

You cannot imagine how much we have been plagued to get crucible[s] that will bear the heat we require and use in our experiments Hessian, Cornish, Pipe-clay crucible all fuse in a few minutes if put into the furnace singly and our only resource is to lute two or three one within another together so that the whole may not fuse before our alloy has had time to form in the centre. I have seen Hessian crucibles becomes [sic] so soft that the weight of 500 grains of metal has made them swell out like a purse and the upper part has fallen together in folds like a piece of soft linen and where three have been put together the two outer ones have in less than half an hour melted off & flown down onto the grate below[.]

From these circumstances you will judge of the heat we get and now I will mention to you an effect which we obtain & one we can’t obtain both of which a little surprised us. The positive effect is the volatilization of silver - We often have it in our experiments sublimed into the upper part of the crucible and forming a fine dew on the sides & cover[.] So that I have no doubts at present on the volatility of silver though I had before.- The non effect is the non reduction of titanium - We have tortured Menachanite pure oxide of titanium the carbonate &c in many ways in our furnace but have never yet been able to reduce it not even in combination with Iron and I must confess that now I am very sceptical whether it has ever been reduced at all in the pure state.

Now I think I have noticed the most interesting points at which we have arrived[.] Pray pity us that after 2 years experiments we have got no farther but I am sure if you knew the labour of the experiments you would applaud us for our perseverance at least[.] We are still encouraged to go on and think that the experience we have gained will shorten our future labours. And if you find the contents of this well covered sheet of paper interesting I shall at some future time do myself the honor & pleasure of sending a continuation of it[.]

If you think any of our results worth notice in the Bibliotheque this letter is free to be used in any way you please³[.] Pardon my vanity for supposing any thing I can assist in doing can be worth attention but you know we live in the good opinion of ourselves & of others and therefore naturally think better of own productions than they deserve[.]

I am My Dear Sir | Very Truly & Sincerely | Your Obliged |

M. Faraday