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364 CHEMISTRY were merely hypothetical. He also sought to analyze organic substances by converting them into carbonic acid and water, thus origina- ting the method now used, the means of execu- ting which have alone been changed. The views of Lavoisier were greatly advanced through the cooperation of his contemporaries and countrymen, Guyton de Morveau (1787- 1816), Fourcroy (1755-1809), and Berthollet (1 748-1 822). With Guyton de Morveau the idea of a rational nomenclature originated, and by his efforts the system now used was produced. The naming of chemical substances had pre- viously been governed by no rules whatsoever, the name given to a new compound depending entirely on the taste and humor of its dis- coverer. With few exceptions no name offered any clue to the chemical properties of the substance. Guyton de Morveau first attempt- ed in 1782 to express an idea of the compo- sition of a substance by its name. This met with violent opposition from all sides. La- voisier, however, had keenly felt the want of a systematic nomenclature ; he therefore ac- cepted the proposition to combine his new theory with the new nomenclature. Associa- ting himself with Guyton de Morveau, Ber- thollet, and Fourcroy, a system was produced so nearly perfect that it only recently experi- enced a change in spite of the immense de- velopment which the science has since under- gone, and the discovery of many substances, the existence of which could not have been foreseen at the time of its formation. Berthol- let was the first chemist of importance who adopted the views of Lavoisier. He afforded them most important aid by many admirable experiments and acute investigations. Although he manifested his own independence by refu- sing to admit that oxygen is the only acidifying principle, two acids, hydrosulphuric and hydro- cyanic, which contain none, being already known, he was nevertheless led into error by Lavoisier's assumption that muriatic acid was composed of an unknown radical united with oxygen; conceiving that chlorine was com- posed of the same radical combined with more oxygen, while the acid which he discovered in chlorate of potash was supposed to contain this radical combined with a still greater quantity of oxygen. This error was not corrected until long afterward. Of the works of Berthollet, that upon affinity was of most importance for theoretical chemistry. While he admitted that all substances have really different degrees of affinity for each other, he sought to prove that what was commonly called affinity depended in great measure upon the relative quantity of the bodies acting on each other (force of mass) ; moreover, that the phenomena of decompo- sition attending such action depend essen- tially upon the physical properties of the com- pounds which are formed. Since affinity can act only through direct contact of the most minute particles of matter, a body may be removed from the field of chemical action either by its insolubility (preponderating cohe- sion), or by its escape in the gaseous form (elas- ticity). According to him, there is no reason why two bodies cannot unite in all possible pro- portions to form chemical compounds, if their cohesion and elasticity, as well as those of the resulting compounds, are equal. The very thorough manner in which Berthollet explained all existing facts by means of this theory, com- bined with the strictness of his conclusions, caused it to receive at once universal attention. A few of his views have been indeed disproved, but as a whole it has since exerted a highly im- portant influence on chemistry. The intimate dependence of the phenomena of decomposition upon the physical character of the resulting compounds, and the great influence which mass exerts in most reactions, have been universally recognized. Berthollet made several important researches. He determined the composition of ammonia, discovered fulminating mercury, and contributed much to the existing knowledge of prussic acid, chlorine, and hydrosulphuric acid. The technical applications of chemistry which he brought about were numerous and exceed- ingly important ; preeminent among them is the use of chlorine in bleaching. The political con- dition of France toward the close of the 18th century exerted a most decided influence upon the progress and direction of chemistry, espe- cially in its application to the arts, and its dif- fusion as a branch of popular knowledge. Pre- vious to this time, technical chemistry was noth- ing but a collection of empirical facts, uncared for by scientific men, and all improvements in the arts depending upon chemical processes were the result of accident. But when France, a country accustomed to purchase from other nations her most important munitions of war, was cut off from outside communication, and compelled to defend herself against all Europe, scientific men, and especially chemists, were called upon to point out the means of producing the materials of war on which the very exist- ence of the nation depended. They were asked to bring forth in a day arts which in other countries had resulted from the experience of years. There was no time now for a repeti- tion of the groping empiricism by means of which these arts had been created. Science has rarely answered practical questions so quickly and clearly. Not only were the requi- site munitions soon prepared, but many arts were developed to an extent previously un- known. A knowledge of the sciences thug came to be considered of great importance fof the welfare of the nation. As soon as law and order had been in a measure restored, new institutions for instruction were formed, to replace those which had been destroyed, in which the study of mathematics and of the physical sciences was made preeminent. This purely material direction has been thoroughly carried out in several of the most renowned schools of France. The influence which it has exerted in diffusing chemical knowledge is