HISTORY. Systematic chemical analysis only dates from the latter half of the eighteenth cen tury, although chemists of an earlier period had accumulated observations which made it possible to test for the presence of many substances. Bergman (1735-84) first attempted to give a plan for systematic qualitative analysis of in organic substances in the wet way. Until the work of Lavoisier (1743-94) had shown the im portance of relations by weight, quantitative de terminations attracted little attention, although such determinations were by no means entirely wanting. After the triumph of Lavoisier's views, the importance of quantitative analysis was fully seen; and the labors of Klaproth (1743 1817), Proust ( 1755-1826), and Vauquelin ( 1703 1829), rapidly enriched chemistry with new methods. But it is to Berzelius (1779-1848) that quantitative analysis owes the heaviest debt. Berzelius published tables of the atomic weights of all the elements well known at that time, and some of his values for these important constants have scarcely been improved on since. In the course of these researches an immense number of new methods were developed. Two of his pupils, Heinrich Rose (1795-1864) and Fried rich `tiler (1800-82), not only added to the methods in use, but published works on inorganic analysis. The final edition of Rose's work, published after his death by his pupil, R. Finkener, remains an invaluable work to the analyst of today. Although K. R. Fre senius (1818-97) added many new methods, his great service, which secures him a conspicu ous place in the history of analytical chemistry, was the collection and comparison of the various methods in use, the publication of text-books, which have formed the models of most others since published, and the founding, of a periodical devoted to analytical chemistry. The last edi
tions of his standard works are in the hands of every analyst.
Volumetric analysis was introduced by Gay Lussac (177S-1850) ; but although he gave the first of his important processes to the world as early as 1824, it was not until the publication of Fr. Mohr's text-book on the subject that volumetric analysis began to rank in importance with gravimetric methods. The ultimate an alysis of organic bodies was attempted with some success by Lavoisier and Berzelius. Gay-Lussac, in 1S15, introduced the use of cupric oxide, and Liebig (1803-73) gave the process essentially its present form. Dumas (1800-84) introduced, in 1830, the method for the determination of nitro gen by direct measurement of the liberated gas, which is still preferred in strictly scientific work to the easier method devised by Kjeldahl.
Many attempts were made to analyze gases in the eighteenth century and in the beginning of the nineteenth, but it is to Bunsen (1811-99) that we owe the perfection of the methods at present in use for gas analysis. The first edition of his text-book, Gasometrische llethodcn, was published in 1857. The improvements since that time have been principally in the direction of adapting the methods to rapid work for tech nical purposes.