The biggest single factor in the production of smoke in a coal burning steam locomotive is the percentage of volatile matter in the coal. Coal mines and railroads would routinely analyze the coal. I have waited to post this looking for some of my records of different coals, but the only analysis I have found is that of the coal we currently use. We specify a maximum of 17% volatile matter. This is what is commonly called Pocohontas. With this it is hard to make smoke. We used to use a coal with 30% volatile matter and it was difficult to keep from making smoke.

The other factors affecting smoke production are the skill of the fireman, how well the locomotive drafts, the size and type of grates, and the arrangement of the ashpans and dampers.Railroads didn't hesitate to change the smokebox arrangement and grates to adapt for different coals.

The other specifications we call for are the maximum percentage of ash, the ash fusion temperature, the maximum percentage of sulphur, the percentage of fixed carbon, the minumum B.T.U.s per pound, and the sizing.

Martyhuck@aol.com