Faraday to Edward Magrath   22 March 1841

56 Kings Road | Brighton | 22 March 1841

Sir

In reply to your letter of the 15th instant I much regret that I shall not be in town on the 26th and shall therefore be unable to attend the committee. In the mean time I send such answers as I can, to the queries in your letter. To the first query I must say, that, the causes of destruction to the binding are not so evident and distinct that one can, without hesitation, refer the evil to its source. As to the second it, certainly, is my opinion that the constant heat and extreme dryness of the rooms are in part the cause of the injury. As to the third:- I think the gas may condense to that end, not only by the heat and consequent comparative dryness which, in such air tight rooms as ours, it produces but also by sulphurous acid and ammoniacal salts which it may convey into the library. To the fourth:- as far as I have yet examined the substance in the leather of the altered binding, it is, principally, muriate and sulphate of ammonia.

I have experiments in hand at the Royal Institution in which Russia, Calf, and Morocco leathers, such as is used for binding, have been prepared, some by immersion into sulphurous acid gas, some by being dipped into solution of muriate of ammonia & then dried; whilst others have been left in their usual state:- and, afterwards, all have been put into a warm air stove where they have remained, I think, above six months but as yet I find no evidence that either the action of these agents, or the dryness, can produce decay like that in the binding on the Athenaeum books. So that I am careful in asserting that any of these circumstances cause the present evil, though they possibly may do so.

Leather, as now prepared for binding, (either calf or Russia) is by no means so strong as it used to be in former years; but the leather I have experimented on is of the modern kind, so that that consideration does not resolve the problem.

My general impression is that the gas, by its great heat and the acid and ammoniacal salts it contributes, is injurious: but I cannot, as yet, carry forward the impression into an assertion. Perhaps also the position of the library over the coffee room may be an assisting circumstance, by tending to prolong the hot-and-dry-state-periods of the upper apartment.

In conclusion, I will beg to suggest an observation or two in relation to this matter, to be made upon the state of the books and room. Are the books on the floor tiers in the same state as those above or those near the ceiling; or are the upper most injured? What is the temperature of the room at the top and bottom during the principal and later parts of the evening? If I were present I should make some further observations as to acidity dryness &c but think it inexpedient to say much on those heads in a letter. It is very probable that sulphuric acid in excess becomes ultimately present in the leather of the binding exposed to the air of the room, and if so, it would, under the circumstances, account for the whole effect. I expect to be in town about the end of the month and will then endeavour to make out this point.

I am My dear Sir | Your Obedient Humble Servant | M. Faraday

E. Magrath Esq | Secretary | &c &c &c