HISTORICAL INTRODUCTION. 23 



Wollaston. In this paper we have the equiva- 

 lents or atomic weights of 73 different bodies, 

 deduced chiefly from a sagacious comparison of 

 the previous analytical experiments of others, 

 ahd almost all of them exceedingly near the 

 truth. These numbers were laid down upon a 

 sliding rule by means of a table of logarithms, 

 and over against them the names of the sub- 

 stances. By means of this rule, a great many 

 important questions respecting the substances 

 contained on the scale may be solved. Hence 

 the scale is of great advantage to the practical 

 chemist, and of course ought to be found in 

 every laboratory. It will give, by bare inspec- 

 tion, the constituents of all the salts contained 

 on it, the quantity of any other ingredient 

 necessary to decompose, and the quantities of 

 the new constituents that will be formed. The 

 contrivance of this scale, therefore, may be con- 

 sidered as an important addition to the atomic 

 theory. It rendered that theory every where 

 familiar to all those who employed it. To it 

 chiefly we owe, I believe, the currency of that 

 theory in Great Britain ; and the prevalence 

 of the mode which Dr. Wollaston introduced, 

 namely, of representing the atom of oxygen by 

 unity, or at least by ten, which comes nearly to Prout . sdis 

 the same thing . c L over y of 



c the relations 



VII. In the year 1815, a paper appeared in between the 

 the 6th volume of the Annals of Philosophy weights. 



84 



