Faraday to Angela Georgina Burdett Coutts   18 May 1859

[Royal Institution embossed letterhead] | London | Albemarle St. W. | 18 May 1859

Dear Miss Coutts

Let me thank you for a very pleasant evening last night¹. My wife could not go but I took two nieces & a nephew & we enjoyed the performance very much.

I suppose you treat Schoenbeins test rightly. Stick a piece up by a pin, outside the window so that it is free in the air - leave it all night - next morning it may shew nothing particular but damp the tip by a touch of clean water (do not dip it into water) and then if there be any ozone action the colour will change to blue faint or stronger according to the action of the ozone[.]

Ever Your faithful Servant | M. Faraday

Address: Miss Coutts | Torquay