Christian Friedrich Schoenbein to Faraday   26 December 1846

My dear Faraday

I am very much obliged to you for the really kind and friendly lines¹ you favoured me with the other day and I won't be long in acknowledging them. As to the late doings of your humble friend they have been of very little consequence ever since my return from England and Mrs. Schoenbein's having been delivered of a girl six weeks ago has interfered with my usual occupations and kept me out of my laboratory. And to tell you the truth my scientific zeal has been checked by a variety of annoying occurrences connected with the guncotton affair. True it is, my knowledge of the World has been vastly increased these last four or five months, but I am afraid that my esteem for mankind has not grown in the same ratio. I could tell you a great many things of an incredible description, but I will not trouble you with detailing facts which I should like never to have become acquainted with myself. So much however I must say that by the occurrences alluded to my temper which is usually not much liable to be ruffled and the placidity of my mind have been suffering these many months. I hope however that time the powerful physician will remedy what has been spoiled. As you take some interest in the substance, I had the fortune or misfortune to find out and to which I have given the name "guncotton"², you will allow me to communicate to you some facts I ascertained previously to having made the noisy discovery. You are perhaps aware that my researches on Ozone led me to think NO<5> a chemical non-entity and consider what they call monohydrate of nitric acid not as NO<5> + HO but NO<4> + HO<2>, the normal nitrates as NO<4> + RO<2>, SO<3> + HO as SO<2> + HO<2> and Rose's Compound³ 2SO<3> + NO<2> as SO<2> + NO<4>. Those views and some other considerations made me conjecture that on mixing together 2(SO<2> + HO<2>) with NO<4> + HO<2>[,] 2SO<2> + NO<4> would be formed and 3HO<2> either eliminated or brought into a loose state of combination with Rose's bisulphate of binoxide of Nitrogen. Supposing such a reaction to take place I of course inferred farther that the acid mixture mentioned would act as a highly oxidizing agent, as a sort of aqua regia in which HO<2> replaces Chlorine and I likewise conjectured that in taking away by the means of oxidable substances HO<2> supposed to exist in the said acid mixture, the latter would exhibit the properties of Rose's Compound. It may be that those hypothetical views are as wrong as they militate against the notions Chymists of the present day are entertaining regarding the nature of nitric acid &c., but in putting myself under their guidance I succeeded in ascertaining a number of facts which appear to me to be entirely novel and not void of scientific interest, facts too which seem to speak rather in favour of my hypothesis. The statements I am going to make will show how far I am entitled to say so. If some flores sulphuris are stirred up with a mixture of nitric acid of 1,5 and common oil of vitriol or chemically pure sulphuric acid of 1,85 a lively disengagement of sulphurous acid gas will issue, the temperature rise, the sulphur disappear and a colourless liquid be left out of which binoxide of nitrogen is abundantly disengaged when mixed up with water. That fluid exhibits in other terms all the chemical bearings of a solution of Rose's 2SO<3> + NO<2> in the monohydrate of sulphuric acid. The action described i.e. the formation of sulphurous acid takes place even at a temperature of 32˚F. (For farther particulars I take the liberty to refer you to a paper which will soon be published in Poggendorff's Annalen on the subject⁴)[.] I have found out that if one drop only of nitric acid of 1,5 be mixed up with four ounces of oil of vitriol, flores sulphuris being added to that mixture will cause a still perceptible formation of sulphurous acid gas which may be easily shown by holding some paste of starch mixed with jodide of potassium and rendered blue by Chlorine over the vessel which holds the acid mixture. The blue colour of the paste will be discharged under the circumstances mentioned. Phosphorus and Selenium are likewise readily oxidized in our mixture at very low temperatures changing the latter such as to render it capable of disengaging binoxide of nitrogen on being mixed with water.

Even Jodine exhibiting so little tendency to unite with oxigen, is at low temperatures readily oxidized in our acid mixture being partly transformed into jodic acid, partly into a lower degree of oxidation (most likely into the jodic oxide of Millon⁵) which unites with sulphuric acid and remains dissolved in the acid mixture⁶. A good deal of jodic acid contaminated with some sulphuric acid is precipitated. To obtain the reaction described it is required to shake powdered jodine with the nitro-sulphuric acid without applying any heat. (For farther particulars see the paper alluded to.)

After having made many experiments with inorganic substances and the acid mixture and recollecting the curious bearings of olefiant gas to Ozone⁷ I tried a number of organic matters and began with common sugar. That substance being in a powdered state at a temperature of about 36˚F was stirred up with a mixture of one volume of nitric acid of 1,5 and two volumes of oil of vitriol. The sugar first assumes a semitransparent appearance but after a few minutes stirring gathers up into a lump of a very tough paste which sticks to the stirring rod and can easily be removed from the acid mixture. On kneading that paste with warm water all the adhering acid particles are taken away and a substance is left, enjoying all the essential properties of resinous matters. It is nearly tasteless yellowish white insoluble or nearly so in water, solid and brittle at low temperatures, easily fusible; at the common temperature it can be malaxated assuming a most beautiful but transient silvery hue, easily soluble in essential oils, ether &c. and going off like gunpowder when heated to a certain degree. Some more statements regarding that curious matter will soon be published in Poggendorff's Annales⁸. After having gone so far, the discovery of those substances of which I took the liberty to send you specimens last March⁹ and of which they talk now so much in Paris, was a matter of course. Guncotton, transparent paper, fulminating paper &c. made rapidly their appearance one after the other and I must not omit to state that all those results were obtained in the months of December (1845) January and February (1846). As to gun cotton I send you an account of an analysis made by Mr. Böttger¹⁰ in Frankfurt who used acetic ether as a solvent to obtain that fulminating matter in a chemically pure state from common gun cotton. Hundred parts of pure guncotton contain

^{11 12}

From hence it appears that the chemical composition of guncotton differs essentially from that of Braconnot's¹³ Xyloidin¹⁴, which latter substance besides, as you well know easily dissolves in strong acetic acid and muriatic acid and is thrown down by water from such solutions whilst guncotton is not acted upon by those acids. Nitric acid of 1,38 readily takes up Xyloidine not to be thrown down again by water, whilst the same acid has no action upon guncotton.

It is perhaps not unknown to you that the french philosophers took no notice of guncotton sooner than after the meeting at Southampton¹⁵ and were in the beginning rather incredulous as to the reality of that substance. But when there could exist no longer any doubt about the matter it was declared by more than one Chymist to be Braconnot's Xyloidine and consequently the invention of the poudre-coton claimed as a French one. Silently I smiled at the assertion knowing it to be unfounded and so very easy to find out the mistake. Indeed in the middle of last month the french academy was informed that as to properties and composition guncotton essentially differs from Braconnot's Xyloidine and the former is made up of what they have called Pyroxyloidine¹⁶. Though the existence of such a substance had even not in the slightest manner been hinted at before the middle of November last, and though it be well known that I have been experimenting upon guncotton the whole year round I am, after an opinion expressed before the french aca<demy> and echoed by many french papers, entitled only t<o the> honor of having first applied to the purposes of g<un> powder what had been discovered by another¹⁷. I openly confess that I cannot conceive with what right such an assertion could have been made, if it have been ever made and I must leave it to the judgment of impartial scientific men to decide who is to be considered as the first discoverer or inventor of gun cotton. I must beg you a thousand pardons for having spoken so much of my little affairs, but as you have yourself expressed a wish to be informed about them you will, I am sure of it, be indulgent. Up to this present moment I have not yet derived any pecuniary advantage from my discovery, I hope however to get something out of it. I was very sorry to learn your being laid up and fervently wish you will soon be able to make use of your limb. Mrs. Schoenbein and the Children are well and beg to be kindly remembered to you and Mrs. Faraday.

Should you think some of the facts mentioned in this letter interesting enough to be communicated in one of your Friday Meetings¹⁸ or elsewhere I don't think I can have any objection to their being made known. Wishing you and your Lady a very happy new year I am

My dear Faraday | Your's | most truly | C.F. Schoenbein

Bâle Dec. 26, 1846.

Address: Doctor M. Faraday | &c &c &c | Royal Institution | London.