"While these varied applications of science to most useful purposes were daily occupations," says Dr. Hayes, "he was pursuing in his laboratory the great study of his life—madder, its products and its application to dyeing—year after year. He deemed the subject exhaustless, and while following the published results of other laborers in the same field as test trials, I happen to know that the most important discoveries, from time to time, were made by him, and often applied, before their publication by others.
"The laboratory, in most busy moments, was exceptionally neat; the deft handling of the apparatus and order of experiments expressed the system of thought."
Soon after removing to Lowell, Dr. Dana became interested in the action of lead upon water, and made a report to the City Council of that city on the danger arising from the use of lead water pipes. His translation and systematic arrangement of the treatise of Tanquerel on Lead Diseases was considered an important contribution to medical knowledge. The discussion of the lead-pipe question gave rise to several pamphlets from Dr. Dana's pen.
Another division of chemistry in which Dr. Dana did valuable work was its application to agriculture. As the outcome of a comprehensive series of experiments and observations, he published, in 1842, The Farmer's Muck Manual of Manures, which was the sheet anchor of libraries in the rural districts of New England for many years. The next year an Essay on Manures submitted by him won the prize offered by the Massachusetts Agricultural Society. He carried into his agricultural investigations the same scientific methods that he had found so important to success in other technical inquiries, and added an overflowing love for the pursuit in all its varied bearings. The younger Silliman wrote of him: "In point of time, originality, and ability. Dr. Dana stood deservedly first among scientific writers on agriculture in the United States."
The fourth edition of the Muck Manual was published in 1855. Its preface states that "the author is not an agriculturist; he does not assume the name even of agricultural chemist," and mentions his position at the works of the Merrimac Company. "While pursuing there," it continues, "during the years 1835, 1836, and 1837, researches on the action of cow dung in calico dyeing, he pushed his inquiries, as a recreation, during his few leisure hours, into the nature and action of manures and of soil. Conversation on these matters with the geological surveyor, and with the agricultural commissioner of Massachusetts, led to a correspondence between the parties, which partly appeared in the published reports on the geology and agriculture of Massachu-
