We now generally prefer to use the name of the element other than oxygen in adjectival form, and to indicate the relatively smaller or greater quantity of oxygen present by modifications in the termination of this adjective. Thus iron protoxide is now generally known as ferr_ous_ oxide, and iron peroxide as ferr_ic_ oxide. But the principles laid down by the four French chemists in 1785-1787 remain as the groundwork of our present system of nomenclature. The antiphlogistic theory was soon adopted by all French chemists of note. We have already seen that Black, with his usual candour and openness to conviction, adopted and taught this theory, and we are assured by Dr. Thomas Thomson that when he attended Black's classes, nine years after the publication of the French system of nomenclature, that system was in general use among the chemical students of the university. The older theory was naturally upheld by the countrymen of the distinguished Stahl after it had been given up in France. In the year 1792 Klaproth, who was then Professor of Chemistry in Berlin, proposed to the Berlin Academy of Sciences to repeat the more important experiments on which the Lavoisierian theory rested, before the Academy. His offer was accepted, and from that time most of the Berlin chemists declared themselves in favour of the new theory. By the close of last century the teaching of Lavoisier regarding combustion found almost universal assent among chemists. But this teaching carried with it, as necessary parts, the fundamental distinction between element and compound; the denial of the existence of "principles" or "essences;" the recognition of the study of actually occurring reactions between substances as the basis on which all true chemical knowledge was to be built; and the full acknowledgment of the fact that matter is neither created nor destroyed, but only changed as to its form, in any chemical reaction. Of Lavoisier's other work I can only mention the paper on "Specific Heats" contributed by Laplace and Lavoisier to the Memoirs of the Academy for 1780. In this paper is described the ice calorimeter, whereby the amount of heat given out by a substance in cooling from one definite temperature to another is determined, by measuring the amount of ice converted into water by the heated substance in cooling through the stated interval of temperature. The specific heats of various substances, _e.g._ iron, glass, mercury, quicklime, etc., were determined by the help of this instrument. As we read the record of work done by Lavoisier during the years between 1774 and 1794--work which must have involved a great amount of concentrated thought as well as the expenditure of much time--we find it hard to realize that the most tremendous political and social revolution which the modern world has seen was raging around him during this time.