Faraday to Francis Maude   17 June 1836¹

R Institution | 17 June 1836

Sir

I am obliged by your kind note & hypothesis but I fear it will not meet the case[.] If we suppose the portion of air very small then the degree of compression which it would receive by the power applied could not raise its temperature so high as to communicate to the large mass of solid matter the temperature it is found to have. If we assume that one half the bulk of the caoutchouc consists of air cells (which I think would not be sufficient to account for the quantity of heat evolved) then mere pressure between the fingers would shew the compressibility of the whole & also evolve warmth whereas that does not come out as the result[.]

Supposing there were any sensible portion of air in caoutchouc then putting the substance under the vacuum of an air pump would cause it to expand & swell up but that does not happen in any sensible degree[.]

The matter is I believe a mystery at present[.]

I am Sir | Your Obliged Servant | M. Faraday

Capt F Maude R.N. | &c &c &c