TDS

"Total Disolved Solids." A sample of boiler water was taken and tested before each steam locomtive was despatched and the total disolved solids in the water was indicated by a hydrometer at a certain temperature.If the total was too high, the boiler would "foam"and allow water into the cylinders,causing lubrication to be washed off pistons and valves.The cure for "Foaming" was to blow water out of the boiler through the "Blow off cocks" and replace with fresh water through the "injectors" until T.D.S. was reduced to a proper level.