PREFACE. 6 



News, Fresenius' Zeitschrift fiir Analytische Chemie, the 

 Journal of the CJiemical Society, the Proceedings of the Royal 

 Society, and the Philosophical Transactions, and of SiUiman's 

 American Journal of Science. I have also made some use of 

 the Philosophical Magazine, and a great deal of use of the 

 Paris Comptes Rendus. These publications are not so in- 

 dexed as to make their contents readily available ; but what 

 appears in the Comptes Rendus is pretty sure to be noticed 

 elsewhere, and T scarcely think that any determinations 

 there published have escaped me. I have also made use of 

 the Bibliotheque Universelle, Archives des Sciences of Geneva, 

 (an incomplete set, unfortunately,) the Zeitschrift fiir Berg- 

 Hiltten-und Salinen-Wesen im Preussischen Staate, Thomson's 

 Annals of Philosophy, Gilbert's Annalen der Physik und der 

 Physikalischen Chemie, the British Association Reports, tlie 

 Transactions of the Royal Society of Edinburgh, the Transactions 

 of the Academies of Brussels and oi St. Petersburg, andi have con- 

 sulted numerous works on chemistry, particularly Berzelius' 

 Lehrbuch der Chemie and Gmelin- Kraut' s Handbuch der Chemie. 

 I have not thought it necessary, or even desirable, to ex- 

 tend my search for atomic weight determinations further 

 back than Wollaston's famous " Table of Equivalents," 

 published in the Philosophical Transactions for 1814. It is 

 true that numerous determinations had been made before 

 that time, byit, with the exception of those mentioned by 

 Wollaston, few which can be of either interest or value to 

 the chemist of the present day, except from a purely histori- 

 cal point of view. From Wollaston's table onwards, I have 

 not felt that the purposes of this paper permitted of any 

 selection between atomic weight determinations, however 

 valueless many of them might appear to my own judgment. 

 Indeed, it has cost me more labor to put many ill-made and 

 ill-reported investigations into proper form for this digest 

 than was required for a majority of those determinations 

 upon which I set the highest value. In the attempt to make 

 a complete collection of the determinations since the time 

 indicated, a few may have escaped my search ; but, if so, 

 they must have fallen singularly dead upon the chemical 

 world, and would be unlikely to repay further labor in seek- 



