アラビアガム
Doubleday had a wide range of interests, in 1851 he won a bronze medal for lace designs made in Coggeshall and shown at the Great Exhibition. He gained the contract with De La Rue for the supply of gum arabic for postage stamps. Gum arabic is made from imported extracts from the acacia tree: in his efforts to find a suitable material which could be grown in England he experimented with imported varieties of comfrey, though the gum produced proved to be unsuitable.