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696. This induced some zealous and active citizens of Lowell to ask me to deliver a course of lectures on agricultural chemistry."

From the notes of these lectures the Muck Manual was prepared. "The work," Dr. Dana states further, "was favorably received at home and abroad, where a considerable portion was reprinted. It has passed through several editions, each being enlarged by the addition of new matter, to keep pace with the times. To the present edition is added an entire new chapter on bones and superphosphates of lime and alkalies. . ..

"One word respecting the title of my book. It is my own. I have neither begged, borrowed, nor stolen it. That last has been done by an English author, who seems to be ashamed, not of the act, but of the name he has filched from me, and so eases his conscience by apologizing for his 'homely title.' I shall not discredit my child by being ashamed of his name. It was good at the christening, and I trust will be thought respectable in manhood."

This edition of the Manual consists of nine chapters. In the first three the author tells the origin and nature of the inorganic ingredients of soil, and in the fourth he describes similarly the organic constituents. Dr. Dana vigorously combats the idea that the kind of rock underlying a district has anything to do with the character of the soil in that district, showing that the soil at any place is a mixture of materials, most of which have been brought from a distance. His full explanations of the several topics that he takes up are summarized in brief statements in a conspicuous type, which he puts forth as the first, second, third, etc., principles of agricultural chemistry. Among these are, "Rocks do not affect the vegetation which covers them."; "Soils contain enough of all the mineral elements to grow any crop" (but it is otherwise with organic constituents); "One base may be substituted for another in an equivalent proportion."

After describing the mutual action of these two classes of substances, he takes up the subject of manure. His chapter opens characteristically:

"The true farmer, no less a sage than the ancient orator who gave to action the first, second, and third place in eloquence, will answer, if it is asked him what is his first requisite. Manure. What second? Manure. What third? Manure. These answers are to be united. Action and manure are the first and last requisites in agriculture; and in the attempt to show what is the last, and how it acts, will be offered every inducement to action."

In the seventy-five pages of this chapter he describes the action of the manures of all domestic animals, also poudrette and certain waste materials valuable as fertilizers—wool washings, soot, bones, and spent lye from soapworks—and gives the chemical composition of nearly all.