Christian Friedrich Schoenbein to Faraday   30 November 1855

My dear Faraday,

Having these many months heard any thing neither from nor of you I had already begun growing anxious about the state of your health when to my great satisfaction I was released from my anxiety by your kind letter of the 6th instant¹ which has made upon my mind the impression that you are a perfectly well doing man. May it please kind providence to preserve you both to your friends and Science for many years to come! This is one of my most ardent wishes, which I cannot help expressing you over and over again; for I see that you have as yet much work to do, many a problem to solve and more than one mystery to divulge to the philosophical world. Indeed, we cannot yet do without the seer and prophet of nature.- Since I wrote you last, we for the first time had here the most unwelcome visit of the Cholera, but thank God, its stay was short and my family as well as my friends were left untouched by it. During the summer Mrs. Schoenbein and the girls spent a couple of months in the Jura mountains, where I joined them now and then to their great satisfaction, the father’s disposition for rambling on green and wooded hills being their’s too, and certainly we did not fail gratifying it to a great extent, walking very often for six or eight consecutive hours together. You will perhaps smile when I tell you that Miss Schoenbein has of late become a very zealous english scholar, reading, writing and speaking away your native tongue in rather a fluent and elegant style. But pray, do not imagine the father to have any part in the proficiency of the daughter, for you must be aware that a parent always proves a very bad master to his children. Certainly on being sometimes called upon to look over the tasks of the young scholar’s, I have an occasion to make some use of the little bit of English I am as yet master of. Number 2 and 3 having caught that liking from her eldest sister, have become pupils of her’s and are going on well enough in their studies. As to me, I can, of course, have no objection to that taste for an outlandish tongue and literature, being myself somewhat suspected of “Anglomanie”. Once speaking of my daughter’s accomplishments I may as well add that she is a partly good musician too, playing the piano not only with facility but I think also with some taste. Being myself a great admirer of the heavenly art of music and after my morning’s schoolmastering sometimes feeling inclined to take a little rest on the sopha, I in a half dozing state of mind listen to Beethoven’s², Mozart’s³, Weber’s⁴ &c delightful compositions being performed by Miss Schoenbein. Having for half an hour or so enjoyed that dreaming pleasure and taken a cup of coffee served up to me by my second daughter I rise again quite refreshed, light my segar and go to my laboratory or to some other business. If you should once mark two o’clock after noon, you will hardly miss the truth, if you imagine your friend lying on his couch and listening to music, an attitude not very picturesque indeed, but nevertheless proving to be an agreeable one to him, that assumes it. Now to finish with my talking of Miss Schoenbein, I will tell you, that she is very desirous of visiting England and seeing the wonders of your country, but I am afraid that her wishes will never be fulfilled, i.e. that she will never prevail upon her father to carry her there. Now before speaking of philosophy, for I cannot help talking to you of my bride, allow me to make a proposal to you, but pray, do not be angry about it. I cannot bear the Idea of seeing you no more in this world and it being very unlikely that I shall be able to cross once more the water and you in comparison to your friend being an independent i.e. moveable man, could you not make up your mind to come over to us with Mrs. Faraday next year and spend a month or two, I won’t say, in Bâle itself but in our fine hilly neighbourhood, where I should try to find out for you a quiet snug corner in which you might carry on a sort of life quite congenial to your taste and Mrs. Faraday’s too. You were, as I hear in Glasgow some months ago⁵; now a journey to Switzerland is not a bit more than a trip to Scotland and in two days, sleeping included you may be here with ease by the way of France. Pray, take that proposal into serious consideration and believe me that nothing in the world could prove to me and my family more gratifying than a visit of your’s and Mrs. Faraday’s would do.- The book⁶, of which I once talked to you⁷, has been out these last three months and as soon as a proper opportunity will offer itself, you shall have it. Being written in german, you will declare it to be a sealed book to you, but you may easily find out a friend of your’s being capable of opening it to you and, indeed, I should like you would acquaint yourself at least with some part of its tenor, as they contain a sort of profession of faith of a friend of your’s. - The third volume of your Researches⁸ has as yet not reached me and putting a high value upon its possession, I beg you to be kind enough as to inquire a little after the fate of that volume.

Now let me talk a little of philosophy and what should or could I begin with but with my favorite subject oxigen, the mere name of which is hated by Mrs. Schoenbein, having become jealous as well as afraid of that seducing and mighty body. Being not quite sure whether I have written you since I got some very remarkable results, even on the risk of telling you the same story twice, I give you a short account of them. You know that I hold oxigen both in its free and bound state to be capable of existing in two allotropic modifications: in the ozonic or active and the ordinary or inactive condition. All the oxy-compounds yielding common oxigen at a raised temperature, I consider to contain ozonized oxigen and I am further inclined to believe that the disengagement of common oxigen from those compounds depends upon the transformation of their ozonized oxigen into inactive one, or as I use to denote that allotropic change of <oring>O into O. Now a general fact is that the oxigen thus set free always contains traces of <oring>O more or less, according to the degree of temperature at which the oxigen happens to be disengaged from those compounds. The lower that degree, the larger the quantity of <oring>O mixt with O, though I must not omit to state, that in all cases that quantity happens to be exceedingly small in comparison to that of O obtained at the same time. The best means of ascertaining the presence of <oring>O is the alkoholic solution of guajacum recently prepared. You know that O does not in the least change the color of that resiniferous liquid, whilst free <oring>O or PbO + <oring>O &c. have the power of coloring it deep-blue. The blue matter is, as I think I have proved it, nothing but guajacum + <oring>O. Now if you heat the purest oxide of gold, platinum, silver, mercury, the peroxides of manganese, lead &c, in fact any substance yielding oxigen, within a small glass tube into which you had previously introduced a bit of filtering paper being impregnated with the said guajacum solution, you will see that bit of paper turning blue so soon as the disengagement of oxigen begins to take place. And all the circumstances being the same, you will farther perceive that the paper is colored most deeply and rapidly by the oxigen being eliminated from that oxycompound, which requires the lowest temperature for yielding part or the whole of its oxigen. Thus the oxigen being disengaged from the oxides of gold, platinum and silver acts more energetically upon the guajacum solution, than the oxigen does being eliminated from the oxide of mercury, the peroxide of manganese &c. I trust these results will be obtained in the Royal Institution just as well as I get them in the laboratory of Bâle, or else my discovery shall be a very poor thing. As there cannot, I should think, be any doubt that all the oxigen being contained for instance in the oxide of silver previously to that compound being decomposed by heat, exists but in one state be that state what it may, how then does it happen, we may ask, that at the same time two different sorts of oxigen O and <oring>O are disengaged from the compound named? The answer to this question seems to me to be, that one of the two kinds of oxigen eliminated must be engendered at the expence of the other, or to speak more correctly, that during the act of the elimination of oxigen from the oxide of silver, part of that oxigen suffers a change of condition. Now the oxides of gold, silver &c. enjoying the power of coloring blue the guajacum solution just so as free <oring>O does I draw from that fact the conclusion that the condition of the oxigen being contained in the oxides of gold, silver &c., is the ozonic one and farther infer, that by far the greatest portion of that <oring>O, under the influence of heat, is transformed into O. Why not the whole of the oxigen being disengaged from those oxides happens to be O, I certainly cannot tell, but I think that the very fact of the mixt nature of the oxigen in question is, in a theoretical point of view, highly important and speaks in favor of my notions rather than against them. Although I have already heavily taxed your patience I am afraid, I cannot yet release you from farther listening to my philosophical talkings, for I have still to speak of a subject that has of late deeply excited my scientific curiosity and taken up all my leisure-time. But to give you an Idea of what I have been doing these last two months, I must be allowed prefacing a little. You know that I entertain a sort of innate dislike to touch any thing being in the slightest way connected with organic Chemistry, knowing too well the difficulty of the subject and the weakness of my powers to grapple with it, but in spite of this wellgrounded disinclination, I have of late and as it were by mere chance been carried in the midst of that field upon the intricacies and depths of which I have been used all my life to look with feelings of unbounded respect and even awe. The picking up of a mushroom has led to that strange aberration of mine and you will ask how such a trifling occurrence could do that. The matter stands thus: What the botanists tell me to be called “Boletus luridus” with some other sorts of mushroom has the remarkable property of turning rapidly blue when their hat and stem happen to be broken and exposed to the action of the atm. air. On one of my ramblings I found a specimen of the said Boletus, perceived the change of color alluded to and being struck with the curious phenomenon, took the bold resolution to ascertain if possible its proximate cause. I carried home the part, set to work and found more than I looked after a thing which luckily enough happens now and then. By the short space being allowed even to the longest letter being prevented from entering into the details of the subject, I confine myself to stating the principal results obtained from my mushroom researches.- Boletus luridus contains a colorless principle being easily soluble in alkohol and as to its relations to Oxigen bearing the closest resemblance to Guajacum, as it appears from the fact, that all the oxidizing agents having the power of blueing the alkoholic solution of guajacum also enjoy the property of coloring blue the alkoholic solution of our mushroom principle and all the desoxidizing substances by which the blue solution of guajacum is uncolored also discharge the color of the blued solution of the Boletus matter. From this fact and others I infer that this mushroom principle, like guajacum, is capable of being associated to <oring>O and is not affected by O. Now the occurrence of a matter being a true brother to guajacum in a mushroom is a fact pretty enough of itself but as to scientific importance far inferior to what I am going to tell you. The fact that the resinous Boletus principle, after having been removed from the mushroom (by means of Alkohol) is not able to color itself spontaneously in the atmospheric air, whilst it seems to have that power so long as it happens to be deposited in the parenchyma of the Boletus, led me to suspect that there exists in the Boletus luridus besides the guajacumlike substance another matter being endowed with the property of exalting the chemical powers of common oxigen and causing that element in its <oring>O condition to associate itself to the resinous principle of the mushroom. And Mr. Schoenbein conjectured correctly, for I found, that in the juice being by pressure obtained from a number of mushrooms belonging to the genera of Boletus and Agaricus and notably from Agaricus sanguineus (upon which I principally worked) an organic matter is contained enjoying the remarkable power of transforming O into <oring>O and forming with the latter a compound from which <oring>O may easily be transferred to a number of oxidable matters both of an inorganic and organic nature and I must not omit to state that the peculiar Agaricus matter, after having been deprived of its <oring>O may be charge with it again by carrying through its solution a current of air. The easiest way of ascertaining the presence of <oring>O in the said Agaricus juice is to mix that liquid with an alkoholic solution of guajacum or the resinous matter of the Boletus luridus. If the juice happens to be deprived of <oring>O, the resiniferous solutions will not be colored blue, but if it contains <oring>O, the solutions will assume blue color, just so as if they were treated with peroxide of lead, permanganic acid, hyponitric acid &c. From the facts stated it appears that the organic matter in question is a true carrier of active oxigen and therefore, when charged with it, an oxidizing agent. Indeed, that matter may in many respects be compared to NO<2>, which as it is well known enjoys to an extraordinary extent the power of instantaneously transforming O into <oring>O and forming a compound (NO<2> + 2<oring>O) with that <oring>O, from which the latter may easily be thrown upon a multitude of oxidable matters. Now in a physiological point of view the existence of such an organic substance is certainly an important fact and seems to confirm an old opinion of mine, according to which the oxidizing effects of the atmospheric Oxigen (of itself inactive) produced upon organic bodies, such as blood &c., are brought about by the means of substances having the power both of exciting and carrying oxigen. Before dropping this subject I must not omit to mention a fact or two more. The peculiar matter being contained in the juice of Agaricus sanguineus &c., and charged with <oring>O, gives up that oxigen to Guajacum and the latter to the resinous matter of the Boletus luridus so that different organic matters capable of being associated to <oring>O as such exhibit different affinities for that oxigen a fact not without physiological importance. Another fact worthy of remark is the facility with which the nature of our agaricus matter may be changed. On heating its aqueous solution, that has the power of deeply blueing the guajacum solution, to the boiling point, it not only looses that property but also the capacity of becoming an oxidizing agent i.e. carrier of oxigen again, however long it may be put in contact with atmospheric air. I am very sorry to be prevented from entering more fully into the details of the subject, but from the little I have said about it you may easily understand why that mushroom affair has of late so much engaged my attention. As to the little bit of philosophical matter, which now and then my letters to you may happen to contain, you have, of course, full liberty to do with it what you think fit.

Before I conclude I must not omit to tell you, that the Swiss Association, which as you know has become the mother of all rambling societies of Europe, will meet at Bâle next mid-summer under the presidency of Peter Merian⁹ a most intimate friend of mine. Now if you should comply with my wishes above expressed, it would be very easy to leave your retreat in our neighbourhood and join us for a day or so. I have no doubt, you would like our meeting, which being a more familiar and much smaller one than that of the british or german association, is for that very reason more comfortable and agreeable. On coming here, you will see many of our Swiss philosophers amongst others our friend de la Rive. I promise you a day in Bâle, which shall please you and remain, I trust, in your memory all your lifetime. If it fall to my lot to see such a day, I shall be the happiest man in the world.

And now I have done, my dear Faraday and ask your kind indulgence for the unusual length of my letter. Pray do not keep so long your silence, as you did the last time and believe me

Your’s | most faithfully | C.F. Schoenbein

Bâle Nov. 30. 1855.

All the members of my family beg to be kindly remembered to you and in doing so I ask you the favor to present my best compliments to Mrs. Faraday. | S.

Mr. Wiedemann also charges me with his compliments to you.