Vlll 



I have been induced to lay the result of my investiga- 

 tions before the public, chiefly for two reasons, with 

 which I think it requisite to acquaint you. The first of 

 these is, the great advantage which medical practitioners 

 will derive from a knowledge of the atomic weights of 

 bodies, and of the weights of the integrant particles of the 

 salts, &c., which they have occasion to employ in their 

 prescriptions. This knowledge will be easily acquired 

 by a perusal of the following pages; and il will enable 

 those who possess it to avoid some very awkward blunders, 

 into which I have observed too many practitioners, even 

 of considerable celebrity, frequently to fall, to the no 

 little inconvenience of their patients. Indeed, till the 

 atomic theory was pretty completely investigated, even 

 chemists themselves were not exempt from such mis- 

 takes; and I could point out, if I thought proper, some 

 remarkable examples of men who would take it amiss if 

 the world did not give them credit for possessing much 

 chemical science, falling into mistakes that no student of 

 mine, who took the trouble to follow and understand the 

 lectures delivered on chemistry in the College of Glas- 

 gow, would run any hazard of committing. It was a wish 

 to enable my students to recollect with ease this im- 

 portant collection of indispensable information, and to 

 put it in the power of other medical students, who are 

 strangers to the lectures which I deliver, to avail them- 

 selves of the benefits to be derived from the facts and 

 the tables in the following pages, that constituted one of 



