The process certainly also offers a solution of the problem of obtaining ammonia from the nitrogen of the atmosphere, but whether this can be done with satisfactory commercial results is a question I cannot at present answer, as I have not been able to secure the data for making the necessary calculations.

I am the more doubtful about this point, as in the course of our investigations I have found means to produce ammonia at small cost and in great abundance from the immense store of combined nitrogen which we possess in our coal fields.

Among the processes for obtaining ammonia from the nitrogen of the air which we investigated, was one apparently of great simplicity, patented by Messrs. Rickman and Thompson.  These gentlemen state that by passing air and steam through a deep coal fire, the nitrogen so passed through is to a certain extent converted into ammonia.  In investigating this statement we found that the process described certainly yields a considerable quantity of ammonia, but when we burned the same coal at a moderate temperature by means of steam alone in a tube heated from the outside, we obtained twice as much ammonia as we had done by burning it with a mixture of air and steam, proving in this case, as in all others, the source of the ammonia to have been the nitrogen contained in the coal.  The quantity of ammonia obtained was, however, so large that I determined to follow up this experience, and at once commenced experiments on a semi-manufacturing scale to ascertain whether they would lead to practical and economic results.

I came to the conclusion that burning coal by steam alone at a temperature at which the ammonia formed should not be dissociated, although it yielded more ammonia, would not lead to an economic process, because it would require apparatus heated from the outside, of great complication, bulk, and costliness, on account of the immense quantity of raw material to be treated for a small amount of ammonia obtainable.

On the other hand, if the coal could be burned in gas producers by a mixture of air and steam, the plant and working of it would be simple and inexpensive, the gas obtained could be utilized in the same way as ordinary producer gas, and would pay to a large extent for the coal used in the operation, so that although only one-half of the ammonia would be obtained, it seemed probable that the result would be economical.

I consequently constructed gas producers and absorbing plant of various designs and carried on experiments for a number of years.  These experiments were superintended by Mr. G. H. Beckett, Dr. Carl Markel, and, during the last four years, by Dr. Adolf Staub, to whose zeal and energy I am much indebted for the success that has been achieved.  The object of these experiments was to determine the most favorable conditions for the economic working of the process with respect to both the cost of manufacture as well as the first cost and simplicity of plant.  The