"The ammoniacal liquor on the surface of the tar-well has been found a very great improvement as a manure for raising crops of grass in this quarter, by being sprinkled on the field in the same way as water is put on public streets in large towns, to keep down dust in dry weather. I have myself seen an experiment of this tried, and can say that part of a field of grass sprinkled in this way, after the first cutting, was far superior to any other part of the field receiving manure of any other kind, and that the part so sprinkled, or showered over, was ready to be cut down a second time in the course of between fourteen days and three weeks; whereas, the other part of the field cut at the same time, was only beginning to spring or rise from the roots in that time. It must be mixed up before use with four parts of common water. In particular, the said experiment of the gas-water has been used by David Nairn, Esq., Doumkilba, near Meigle, in this neighborhood, with success; and I am informed that he has purchased and taken a lease of the ammoniacal liquor from different gas-companies in this country. "I am convinced much good might be derived from different qualities of the refuse products of gas-works as manure. An inquiry into this subject would remunerate the engineer or agriculturist to the full, and would besides confer a considerable benefit upon his fellows, and give that practical proof of the correctness of a theory so welcome to the man of science." "The fertilizing power of gypsum has been explained by its supposed action on the ammonia which is presumed to exist in the atmosphere. If this be the true explanation, a substance containing ammonia should act _at least_ as energetically. At all events, the action of foldyard manure and of putrid urine, is supposed to depend chiefly on the ammonia they contain or give off. "Now among the substances containing ammonia in large quantity, the ammoniacal liquor of the gas-works is one which can easily be obtained, and can be applied in a liquid state at very little cost. It must be previously diluted with water till its taste and smell become scarcely perceptible. "I would propose therefore, as a further experiment, that along with one or more of the substances above mentioned, the ammoniacal liquor of the gas-works should be tried, on a measured portion of ground, and, if possible, in the same field.