696 POPULAR SCIENCE MONTHLY. 



setts. 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 pre- 

 pared. " The work," Dr. Dana states further, " was favorably 

 received at home and abroad, where a considerable portion was 

 reprinted. It has pass,ed 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 con- 

 science 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 sub- 

 stances, 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 requi- 

 sites 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 composi- 

 tion of nearly all. 



