Red litmus paper, from the portable laboratory owned by Dr. H.G Butterfield, unsigned, 1930-1940 Red litmus paper 1930-1940
Neutral litmus paper, from the portable laboratory owned by Dr. H.G Butterfield, by Johnson and Sons, Hendon, London, 1930-1940 Neutral litmus paper 1930-1940
Carton with 5 of original 6 litmus cartridges, red - each containging 144 strips of litmus paper. Price 4d each, 1/10 per box. Artisto Litmus Cartridges
