92 Memoir of the late 



of oxygen in an oxide. He thus introduces this important 

 invention, which has been almost universally adopted in the 

 science : — li As colour is a very ambiguous criterion for 

 distinguishing metallic oxides, I have been accustomed for 

 some time to denote the oxide with a minimum of oxygen, 

 by prefixing the Greek ordinal number to the term oxide. 

 Thus, protoxide of lead is lead united to a minimum of oxy- 

 gen ; the oxide, with a maximum of oxygen, I call peroxide. 

 Thus, brown oxide of lead is the peroxide of lead. I deno- 

 minate the intermediate degrees of oxidizement by prefixing 

 the Greek ordinals, 2d, 3d, 4th, &c. Thus, deutoxide is 

 the second oxide of lead, tritoxide of cobalt the third oxide 

 of cobalt, and so on." This paper was translated and pub- 

 lished in France ; the nomenclature was speedily introduced 

 into that country. But the improvements which he after- 

 wards adopted, by denoting the exact number of atoms of 

 oxygen present by the Latin, and those of the base by the 

 Greek numerals, and used in Great Britain, never super- 

 seded, in that country, the original suggestion in the above 

 note. 8. All these inventions were merely particular parts 

 of a systematic arrangement adopted in his " System of 

 Chemistry," a work which, if carefully examined with a 

 philosophic eye, will be found to have produced beneficial 

 results to chemical science similar to those which the systems 

 of Ray, Linnseus, and Jussieu effected for botany. In his 

 second edition, published in 1804, (the first large edition 

 having been sold in less than ten months,) he divided the 

 consideration of chemical bodies into — Book I. Simple sub- 

 stances : 1. Confinable bodies, including oxygen, simple com- 

 bustibles, simple incombustibles, metals ; 2. Unconfinable 

 bodies, comprising heat and light. Book II. Compound 

 bodies : 1. Primary compounds ; 2. Secondary compounds, 

 &c. It is most interesting to observe how his plan was 

 developed with the progress of the science in the different 

 editions. It is sufficient to say that it was generally con- 

 sidered as a masterly arrangement, and used to be quoted 

 by the Professor of Logic in Edinburgh, as an admirable 

 example of his analytic and synthetic methods. Previous to 

 the publication of his " System" British chemists were con- 



