Letter from J [John] Brown, Longhurst, Dunmurry, Belfast, to [Joseph] Larmor Brown describes putting 32 sheets of parchment paper in a pile with tin foil at the bottom, charging them from the bottom, so that the pile cracked and adhered. He describes the effects and charges - the alterative charge surprised him. Common parchment paper is not nitrocellulose as Larmor supposed. 'Would it not be risky [?] to let off sparks on nitrocellulose paper i.e. guncotton. It would therefore probably not explode'. He encloses a sample of what he used [not present]. 30 January 1903