Charles Giles Bridle Daubeny to Faraday   12 November 1831

Oxford Nov. 12th. 1831

Dear Sir,

I have to thank you for a copy of your late Memoir¹, which arrived the other day with one for Professor Rigaud².

I am send[ing] you a Prospectus of the British Association for the promotion of Science³ which I hope you will approve, though I am sorry to find it is uncertain whether we shall have the advantage of your personal cooperation <-> Actively engaged as you always are in the advancement of knowledge you have doubtless the best possible right to consult your own feelings in this matter, and I only hope that if you should not feel yourself equal to visiting us on this public occasion, I shall have the pleasure of seeing you here at a time of less bustle, whenever you may find a little change of scene agreeable -

As you are engaged in experiments on Magnetism, I will state to you a fact which seemed to me curious, though I am not well enough read in the recent discoveries of that branch of Physics to feel confident as to its novelty - Having constructed a temporary Magnet of soft Iron in a horse-shoe form after Professor Moll’s method which supported from 100 to 140 lbs⁴ - I was surprised to find, that after the communication with the battery was interrupted, it still supported the Armature weighing 3 lb, and weights attached amounting to about 17lb. - Now this was not owing to any induced Magnetism, for the Iron exerted no influence upon the needle or on the lightest Iron filings brought near it and when the Armature had been removed for a single second, the Iron did not attract it in the least - I conceive that the effect could only arise from the adhesion between the two smooth surfaces of the Iron, and Armature, and yet the surfaces presented, by each extremity, of the horse-shoe magnet, were not more than 1 1/4 Inch in diameter, each. If so, the experiment appears a good illustration of the extreme nearness of contact brought about by magnetic attraction between two metallic surfaces and proves to us that in estimating the force of a magnet, we ought to make a deduction for the weight which the Armature takes up in consequence of its adhesion to the attracting surface. -

Are you aware of the extreme incombustibility of coke completely deprived of its bitumen? I have a specimen from a coal pit of Ld Fitzwilliam’s⁵ which had caught fire, extremely light owing to its reticulated or honeycombed structure wh. I have been unable to burn even by exposure to the Oxy-hydrogen blowpipe, by which I have often readily inflamed the Diamond - Its non- inflammability is I suppose in part owing to the thinness of its texture, which causes it to have a large surface radiating heat in proportion to the substance in which heat can be accumulated - I have also tried without success to burn it away by heating it red hot with nitrate of ammonia -

I shall send you a copy of a paper of mine, which will appear in the next number of Jameson’s⁶ Journal in wh. I hope to prove two points 1st. that warm springs are for the most part of volcanic origin & 2dly. that their products can only be explained by the chemical theory of volcanoes wh. I have adopted⁷.

Believe me Yours most truly | Chas. Daubeny

Address: M. Faraday Esq. | Royal Institution | Albemarle Street