_Superheated Steam._--The effective application of the energy of the high pressure steam is probably one of the most important problems in paper mill economy. The use of superheated steam is being extended in every direction, and, in addition to the advantages obtained in the steam engine itself, its wider possibilities for the boiling of esparto, wood, and fibres generally have been noted. The following case may be quoted as the result of a trial at a paper mill, showing for stated conditions the advantages of superheated steam:-- --------------------------+-------------+---------- -- | Superheated | Ordinary | Steam. | Steam. --------------------------+-------------+---------- Duration of test hours | 26 | 34 | | Coal consumed (lbs.)-- | | Per hour | 610·5 | 661·5 Per 1 h.-p. hour | 1·83 | 2·08 | | Water evaporated (lbs.)-- | | Per hour | 4,832 | 5,679 Per 1 h.-p. hour | 14·55 | 17·8 From and at 212° F. | 8·7 | 8·94 | | Steam, temperature F. | 464 | 334 Pressure | 90·3 | 90·8 | | Steam engine-- | | 1 h.-p. total | 331·5 | 323·2 Temperature F. | 381·8 | 333·8 | | Coal used per 1 h.-p.-- | | Per hour at boiler | 1·83 | 2·08 --------------------------+-------------+---------- This appears to show a saving of 12 per cent. _Gas Producers._--The substitution of gas for steam in the paper mill has not yet proved a success. The fact that heat is required for the drying cylinders of a paper machine, and that the heat is most cheaply and readily obtained in the form of exhaust steam from the engines driving the paper machine, militates considerably against economies which might otherwise be possible. The difficulties of heating such cylinders, or rather of properly controlling and regulating the temperature by any other means than steam, may easily be surmised. Gas engines of over 200 h.-p. seem to give considerable trouble at present, but no doubt in course of time the required improvements will be effected. It is generally supposed that gas producers can only be economical when utilised for the production of gas on a large scale, and for distribution to engines of smaller capacity than the main steam engine required in a paper mill. The peculiar conditions of the manufacture of paper do not appear to be favourable to the adoption of the gas producer system in its present form.