It may be surmised that the quantitative measures of most physical properties will be found to be connected with the chemical nature of substances.
It must remain constant for the same substance at any temperature and in any form) that quantitative relations between refractivity and chemical composition can be derived.
Fresenius, Qualitative and Quantitative Analysis, Eng.
Lavoisier may be justly regarded as the founder of modern or quantitative chemistry.
The methods of chemical analysis may be classified according to the type of reaction: (I) dry or blowpipe analysis, which consists in an examination of the substance in the dry condition; this includes such tests as ignition in a tube, ignition on charcoal in the blowpipe flame, fusion with borax, microcosmic salt or fluxes, and flame colorations (in quantitative work the dry methods are sometimes termed " dry assaying "); (2) wet analysis, in which a solution of the substance is treated with reagents which produce specific reactions when certain elements or groups of elements are present.
The researches of Julius Thomsen and others have shown that in many cases definite conclusions regarding constitution can be drawn from quantitative measurements of the heats of combustion; and in this article a summary of the chief results will be given.
The principal object of this more recent research has been the determination of the quantitative amount of chemical change associated with the passage for a given time of a current of strength known in electromagnetic units.
In quantitative analysis the methods can be subdivided into: (a) gravimetric, in which the constituent is precipitated either as a definite insoluble compound by the addition of certain reagents, or electrolytically, by the passage of an electric current; (b) volumetric, in which the volume of a reagent of a known strength which produces a certain definite reaction is measured; (c) colorimetric, in which the solution has a particular tint, which can be compared with solutions of known strengths.
In quantitative estimations it is generally weighed as oxide, after precipitation as sulphide or carbonate, or in the metallic form, reduced as above.
Fleming, " A Note on a Form of Magnetic Detector for Hertzian Waves adapted for Quantitative Work," Proc. Roy.
The most important subjects of his inquiries are enumerated by Forbes under the following five heads: - (1) The laws of polarization by reflection and refraction, and other quantitative laws of phenomena; (2) The discovery of the polarizing structure induced by heat and pressure; (3) The discovery of crystals with two axes of double refraction, and many of the laws of their phenomena, including the connexion of optical structure and crystalline forms; (4) The laws of metallic reflection; (5) Experiments on the absorption of light.
This section treats of the qualitative detection and separation of the metals, and the commoner methods employed in quantitative analysis.
By his insistence upon the use of the balance as a quantitative check upon the masses involved in all chemical reactions, Lavoisier was enabled to establish by his own investigations and the results achieved by others the principle now known as the " conservation of mass."
Such a determination is qualitative, the constituent being only detected or proved to be present, or quantitative, in which the amount present is ascertained.
His text-books on the subject, of which the Qualitative appeared in 1841, and the Quantitative in 1846, have a world-wide reputation, and have passed through several editions.
Since then the subject has been extensively studied, more particularly by Alexander Classen, who has summarized the methods and results in his Quantitative Chemical Analysis by Electrolysis (1903).
We shall here consider the qualitative and quantitative determination of these elements.
Cohn (Quantitative, 1903); F.
" The variety of individuals," says Albert, " depends entirely upon the division of matter," and Aquinas says the principle of the diversity of individuals of the same species is the quantitative division of matter," which his followers render by the abbreviated phrase materia quanta.
Various methods have been devised for the quantitative determination of phenol.
He emphasized that the practical training should include (1) the qualitative and quantitative analysis of mixtures, (2) the preparation of substances according to established methods, (3) original research - a course which has been generally adopted.
Quantitative Inorganic Analysis.
Owing to the difficulty of determining the magnetization I and the susceptibility K with accuracy, it has not yet been possible to submit this formula to a quantitative test, but it is said to afford an indication of the results given by actual experiment.
It is part of the general theory of quantitative relation, and in its elementary stages is a suitable subject for graphical treatment (ï¿½ 31).
The quantitative precipitation of metals by the electric current, although known to Michael Faraday, was not applied to analytical chemistry until O.
Quantitative methods are divided into four groups, which we now pass on to consider in the following sequence: (a) gravimetric, (0) volumetric, (7) electrolytic, (5) colorimetric.
Combustion is a familiar example of the transformation of chemical energy into heat and light; the quantitative measures of heat evolution or absorption (heat of combustion or combination), and the deductions therefrom, are treated in the article Thermochemistry.
A tolerably evident shortcoming of such a doctrine is that, while declaring the quantitative determination of matter to be the individual element in the individual, it gives no account of how such quantitative determination arises.
His version of the methodological assumption of constancy in the quantitative aspects of phenomena, seems a very unsuitable basis for a philosophy of progress.
Schott gives the following as the result of measurements of transparency by means of a white disk at 23 stations in the open ocean, where quantitative observations of the plankton under i square metre of surface were made at the same time.
The thermal G G detectors are especially useful for the purpose of quantitative measurements, because they indicate the true effective or square root of mean square value of the current or train of oscillations passing through the hot wire.