SAMUEL LUTHER DANA. 



313 



West Point during the War of 1812, graduating in 1814. He 

 remained in military life until his death in 1833. 



Samuel did not return to the law, but took up the study of 

 medicine under Dr. Bancroft, of Groton. Receiving his med- 

 ical degree in 1818, he began the practise of his profession 

 in Gloucester, Mass. The next year he married Ann Theo- 

 dora, daughter of Rev. Joseph Willard, D. D., who had been 

 President of Harvard College from 1781 till his death 

 in 1804. 



Dr. Dana now took up his abode in Waltham, Mass., where 

 he practised medicine until 1826. Toward the close of .this 

 period he established a laboratory for the production of sul- 

 phuric acid and bleaching salts. This enterprise soon devel- 

 oped into the Newton Chemical Company, of which he was 

 chemist till 1834. His friend Dr. A. A. Hayes, in the memo- 

 rial pamphlet of the Dana family, has testified to his wide 

 knowledge of the properties of substances and his great 

 fertility in original devices for general and technological 

 work. In his manufacture of acids and other chemicals im- 

 proved plans and processes were early employed, and Dr. 

 Hayes mentions especially Dana's device for deoxidizing man- 

 ganic oxide by heating it with sulphur, in order to form from 

 it (with pyroligneous acid) a crude manganous acetate, then 

 largely used in dyeing a fast brown. 



The second of Dr. Dana's published writings was issued in 

 1833, while he was on a visit to England. It was a clear ex- 

 position of the chemical changes occurring in the manufacture 

 of sulphuric acid. 



In the following year Dr. Dana became resident and con- 

 sulting chemist to the Merrimac Manufacturing Company, at 

 Lowell, Mass., in which position he remained for the rest of 

 his life a period of thirty-four years. The improvements 

 which he introduced into the processes carried on in the 

 mills of this company were many and important. Dr. Hayes 

 gives an outline of these. He undertook systematic re- 

 searches on the action of the dung of beeves then used for 

 removing the excess of mordant in printing calicoes with 

 madder which resulted in the discovery that crude phos- 

 phates in a bath with bran are a complete substitute for the 

 expensive and disgusting material before deemed indispen- 

 sable. Arseniates, which are cheaper than phosphates, were 



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