The Papers of Alexander Johnston consists of manuscripts written by Johnston, commissioned by him, or simply presented by him to the Society. These are:

• Portfolio of material donated by Sir Alexander Johnston to the Royal Asiatic Society
• 'A Summary of the Principle Evidence for the Truth, Divine Origin of the Christian Revelation' by Beilby, Lord Bishop of London, translated J.G. Philips & C. de Saram into Sinhalese.
• "Moses in the Bulrushes - A Sacred Drama" and "Joseph" by Hannah More, translations in Sinhalese.
• Report on tumuli or barrows in the Sardis region (Turkey) by George Hale.