Berzelius, and somewhat later, in the experiments of the Belgian chemist J.
Berzelius saw at once that it afforded an admirable test for the correctness of Dalton's views, and he made numerous experiments expressly designed to test the law.
Berzelius took 8 grams of copper, converted it into the coloured chloride, and sealed up the whole of this in solution, together with a weighed strip of copper.
Berzelius tested this prediction.
On account of this difficulty, the atomic weights published by Dalton, and the more accurate ones of Berzelius, were not always identical with the values now accepted, but were often simple multiples or submultiples of these.
Berzelius by the dry distillation of tartaric or racemic acids (Pogg.
The atomic weight was determined by Berzelius, Erdmann and Marchand, Dumas and Stas.
Explanations had indeed been put forward by men as eminent as Berzelius and Liebig, but they lacked experimental foundation.
Berzelius; and ten years later he accepted the office of principal of the university of Edinburgh, the duties of which he discharged until within a few months of his death, which took place at Allerly, Melrose, on the 10th of February 1868.
He was a most prolific writer, 364 papers appearing under his name in the Royal Society's Catalogue, and he carried on a large correspondence with other men of science, such as Berzelius, Faraday, Liebig and Wohler.
As to the detergent action of a soap, Berzelius held that it was due to the free alkali liberated with water; but it is difficult to see why a solution which has just thrown off most of its fatty acids should be disposed to take up even a glyceride, and, moreover, on this theory, weak cold solutions, in which the hydrolysis is considerable, should be the best cleansers, whilst experience points to the use of hot concentrated solutions.
Berzelius, who, fired with enthusiasm by the original theory of Dalton and the law of multiple proportions, determined the equivalents of combining ratios of many elements in an enormous number of compounds.2 He prosecuted his labours in this field for thirty years; as proof of his industry it may be mentioned that as early as 1818 he had determined the combining ratios of about two thousand simple and compound substances.
We may here notice the important chemical symbolism or notation introduced by Berzelius, which greatly contributed to the definite and convenient representation of chemical composition and the tracing of chemical reactions.
2 Berzelius, however, appreciated the necessity of differentiating the atom and the molecule, and even urged Dalton to amend his doctrine, but without success.
A great advance was made by Dalton, who, besides introducing simpler symbols, regarded the symbol as representing not only the element or compound but also one atom of that element or compound; in other words, his symbol denoted equivalent weights.4 This system, which permitted the correct representation of molecular composition, was adopted by Berzelius in 1814, who, having replaced the geometric signs of Dalton by the initial letter (or letters) of the Latin names of the elements, represented a compound by placing a plus sign between the symbols of its components, and the number of atoms of each component (except in the case of only one atom) by placing Arabic numerals before the symbols; for example, copper oxide was Cu +0, sulphur trioxide S+30.
At a later date Berzelius denoted an oxide by dots, equal in number to the number of oxygen atoms present, placed over the element; this notation survived longest in mineralogy.
Although the system of Berzelius has been modified and extended, its principles survive in the modern notation.
Berzelius objected to the hypothesis that if two elements form only one compound, then the atoms combine one and one; and although he agreed theory.
While successfully investigating the solid elements and their compounds gravimetrically, Berzelius was guilty of several inconsistencies in his views on gases.
Berzelius elevated this theory to an important position in the history of our science.
His terminology was vague and provoked caustic criticism from Berzelius; he assumed that all molecules contained two atoms, and consequently the atomic weights deduced from vapour density determinations of sulphur, mercury, arsenic, and phosphorus were quite different from those established by gravimetric and other methods.
Gerhardt found that reactions could be best followed if one assumed the molecular weight of an element or compound to be that weight which occupied the same volume as two unit weights of hydrogen, and this assumption led him to double the equivalents accepted by Gmelin, making H= 1, 0 =16, and C = 12, thereby agreeing with Berzelius, and also to halve the values given by Berzelius to many metals.
The development of the atomic theory and its concomitants - the laws of chemical combination and the notion of atoms and equivalents - at the hands of Dalton and Berzelius, the extension to the modern theory of the atom and molecule, and to atomic and molecular weights by Avogadro, Ampere, Dumas, Laurent, Gerhardt, Cannizzaro and others, have been noted.
The growth of chemical literature since the publication of Lavoisier's famous Traite de chimie in 1789, and of Berzelius' Lehrbuch der Chemie in 1808-1818, has been enormous.
In the same year as Klaproth detected uranium, he also isolated zirconia or zirconium oxide from the mineral variously known as zircon, hyacinth, jacynth and jargoon; but he failed to obtain the metal, this being first accomplished some years later by Berzelius, who decomposed the double potassium zirconium fluoride with potassium.
Berzelius was an early worker in this field; he was succeeded by Bunsen, and Deville and Debray, who worked out the separation of rhodium; and at a later date by P. T.
Considerable uncertainty existed as to the atomic weights of these metals, the values obtained by Berzelius being doubtful.
The discovery of boron by Gay Lussac and Davy in 1809 led Berzelius to investigate silica (silex).
At the same time Berzelius obtained the element, in an impure condition, by fusing silica with charcoal and iron in a blast furnace; its preparation in a pure condition he first accomplished in 1823, when he invented the method of heating double potassium fluorides with metallic potassium.
In the same year Berzelius discovered selenium in a deposit from sulphuric acid chambers, his masterly investigation including a study of the hydride, oxides and other compounds.
Arfvedson, a pupil of Berzelius, detected a new element, which he named lithium, in various minerals - notably petalite.
In 1845 a further contribution to the study of allotropy was made by Anton Schrotter, who investigated the transformations of yellow and red phosphorus, phenomena previously noticed by Berzelius, the inventor of the term " allotropy."
The allotropy of selenium was first investigated by Berzelius; and more fully in 1851 by J.
Klaproth, and especially by Berzelius; these chemists are to be regarded as the pioneers in this branch of descriptive chemistry.
Hisinger and Berzelius, was of ceria, the oxide of cerium, in the mineral cerite found at Ridderhytta, Westmannland, Sweden.
At this time there existed a belief, held at a later date by Berzelius, Gmelin and many others, that the formation of organic compounds was conditioned by a so-called vital force; and the difficulty of artificially realizing this action explained the supposed impossibility of synthesizing organic compounds.
Berzelius, in 1813 and 1814, by improved methods of analysis, established that the Daltonian laws of combination held in both the inorganic and organic kingdoms; and he adopted the view of Lavoisier that organic compounds were oxides of compound radicals, and therefore necessarily contained at least three elements - carbon, hydrogen and oxygen.
The binary conception of compounds held by Berzelius received apparent support from the observations of Gay Lussac, in 1815, on the vapour densities of alcohol and ether, which pointed to the conclusion that these substances consisted of one molecule of water and one and two of ethylene respectively; and from Pierre Jean Robiquet and Jean Jacques Colin, showing, in 1816, that ethyl chloride (hydrochloric ether) could be regarded as a compound of ethylene and hydrochloric acid.
However, in 1833, Berzelius reverted to his earlier opinion that oxygenated radicals were incompatible with his electrochemical theory; he regarded benzoyl as an oxide of the radical C 14 H 1Q, which he named " picramyl " (from 7rucp6s, bitter, and &uvyalk, almond), the peroxide being anhydrous benzoic acid; and he dismissed the views of Gay Lussac and Dumas that ethylene was the radical of ether, alcohol and ethyl chloride, setting up in their place the idea that ether was a suboxide of ethyl, (C2H5)20, which was analogous to K 2 0, while alcohol was an oxide of a radical C 2 H 6; thus annihilating any relation between these two compounds.
The radical theory, essentially dualistic in nature in view of its similarity to the electrochemical theory of Berzelius, was destined to succumb to a unitary theory.
Vigorous opposition was made by Liebig and Berzelius, the latter directing his attack against Dumas, whom he erroneously believed to be the author of what was, in his opinion, a pernicious theory.
More emphatic opposition to the dualistic theory of Berzelius was hardly possible; this illustrious chemist perceived that the validity of his electrochemical theory was called in question, and therefore he waged vigorous war upon Dumas and his followers.
Still, till the last Berzelius remained faithful to his original theory; experiment, which he had hitherto held to be the only sure method of research, he discarded, and in its place he substituted pure speculation, which greatly injured the radical theory.
Unwilling to discard the strictly unitary views of these chemists, or to adopt the copulae theory of Berzelius, he revived the notion of radicals in a new form.
The rapidity of the method, and the accurate results which it gave in the hands of a practised experimenter, led to its systematization by Jens Jakob Berzelius and Johann Friedrich Ludwig Hausmann, and in more recent times by K.
The formulation of the atomic theory by John Dalton gave a fresh impetus to the development of quantitative analysis; and the determination of combining or equivalent weights by Berzelius led to the perfecting of the methods of gravimetric analysis.
Since the time of Berzelius many experimenters have entered the lists, and introduced developments which we have not space to mention.
We may, however, notice Heinrich Rose i and Friedrich WShler, 2 who, having worked up the results of their teacher Berzelius, and combined them with their own valuable observations, exerted great influence on the progress of analytical chemistry by publishing works which contained admirable accounts of the then known methods of analysis.