PREFACE. V 



of Nicholson, Aikins, and Ure, the Compendium of Dr. Hare, the 

 Dispensatory of Dr. Coxe, the Technology of Dr. Bigelow, the 

 Operative Chemist of Gray, and the Chemical Manipulation of Mr. 

 Faraday ; the System of the late Dr. Murray, and his Elements, ably 

 edited by his son ; as also the writings of Mr. Dalton ; the works of 

 Lavoisier, Chaptal, Berthollet, and Fourcroy, the System of Thenard, 

 in its most recent edition, and his miscellaneous writings, especially 

 in connexion with Gay-Lussac ; and those of Dr. Priestley, Bishop 

 Watson, Mr. Parkes, Prof. Berzelius, and Sir H. Davy, including 

 also his Elements these are among the leading authorities, although 

 it would be easy to increase the catalogue.* 



A recent work by Dr. Turner, of the London University, has 

 been of great utility. It is highly scientific and very exact, particu- 

 larly on the facts and doctrines of definite and multiple proportions, 

 and combining equivalents ; and many of its details have been adopted. 



But the work to which, more than to any other, the author of this 

 is indebted, is the Elements of Dr. Henry. All its numerous edi- 

 tions have been attentively studied, and among the facts that have 

 been cited from it, the statements of the proportions of bodies, and 

 especially of the salts, are the most prominent. In numerous critical 

 comparisons, made between it and the original memoirs, abundant 

 evidence has been obtained of the great exactness of the respectable 

 author, whose abstract always reflects an image of the original, 

 diminished indeed, but perfect in every feature. No writer on 

 chemistry, in the English language, surpasses Dr. Henry in fidelity, 

 perspicuity and good judgment. For twenty years, his work was the 

 text book of the classes in this Institution, and it ceased to be used 

 here only when, on account of its increased size and cost, it ceased 

 to be reprinted. Three editionsf of it with notes, were published ex- 

 pressly for the students of Yale College ; there have been three 

 English editions since the latest American, J and the author's eleventh, 

 with his last revision, has, through his kindness, been just received. 



* Many French as well as English Journals of Science have been also examined. 



t Besides two subsequently, by Professors Coxe and Hare, of the Univ. of Penn. 



t Since it has become difficult to obtain this work, the valuable Manual of Dr. 

 Webster, on the basis of Brande, has 'been recommended to the classes. Few 

 works on Chemistry contain so much important information. 



