314 



PIONEERS OF SCIENCE IN AMERICA. 



afterward substituted for them on the suggestion of Mercer, 

 and are the worldwide reliance of print manufacturers at the 

 present day. 



Of the same systematic character was his study of the 

 chemical changes involved in the process of bleaching cotton 

 fabrics preparatory to printing them. This inquiry resulted in 

 his inventing a method which not only received high com- 

 mendation as scientific work but was universally adopted in 

 practice. As most of Dr. Dana's researches were made for 

 the exclusive benefit of the company with which he was con- 

 nected, their results were not always published promptly, and 

 hence the abilities that might have won a high meed of fame 

 remained known to only a small circle. His discoveries with 

 respect to bleaching cotton, however, were published in the 

 Bulletin de la Societe Industrielle de Mulhouse in 1838. The 

 principles therein established have led to the American method 

 of bleaching, of which Persez, in his Traite" de 1'Impression 

 des Tissues, says that " it realizes the perfection of chemical 

 operations." 



The Merrimac Mills were at first run by water power 

 alone, but when the works were extended this was supple- 

 mented by the use of steam. Dr. Dana was now called to the 

 new field of engineering, in addition to his other duties. His 

 development of the whole subject of the evaporative power 

 of coal and the economical disposition of the heat in steam 

 and in water of condensation is a masterly effort, embracing 

 every detail, and was in advance of any published results of 

 the time. 



For several years before he became a resident of Lowell, 

 Dr. Dana was frequently called to that city as a consulting 

 chemist. He was also one of the chemists consulted by the 

 water commissioners of both Boston and New York prior 

 to the introduction of the Cochituate and Croton water re- 

 spectively. 



" 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 labourers in the same field as test 

 trials, I happen to know that the most important discoveries, 



