Sinopsis
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1900 Excerpt: ...has the value 2612. The lower values for chlorine, bromine and iodine are for organic compounds, the higher values are those which they possess in the salts. Kanonnikoff1 has also determined a few atomic refractions. His results, which do not differ much from those of Gladstone, are given on the next page. 1 J.f. pr. Oh. (2), 31, p. 339. The periodicity of the atomic refractions is unmistakable, the maxima falling on the elements of the fifth series, except in the case of arsenic. It is difficult to localise the minimum elements. They hover between groups seven, eight, one and two. Obviously, when we get better data, we shall arrive at more uniform results. The Spectra of the Elements. The study of spectra is of the utmost importance to the physical chemist, for it teaches more about the nature of the atoms than any other property of matter. Owing to the immense amount of work done in the domain of spectrum analysis, it will not be possible here even to give a short sketch of the subject, but only those portions which are of vital importance for our present consideration will be treated of. There are three great classes of spectra:--Emission Spectra, Absorption Spectra, Phosphorescence Spectra. For our purpose we need only consider the first class--Emission spectra. We have here again three great divisions:--(1) Flame spectra; (2) Arc spectra; (3) Spark spectra. The substances giving flame spectra are few in number. They are lithium, sodium, potassium, rubidium, caesium, barium, strontium, calcium, indium, gallium, thallium, boron, and one or two more. The spark spectra are usually employed as all elements give them. For gases this is the only method possible. However, in some cases, the use of the arc spectrum is preferable, e.g., carbon. The spectra obtai...
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Reseña del editor
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1900 Excerpt: ...has the value 2612. The lower values for chlorine, bromine and iodine are for organic compounds, the higher values are those which they possess in the salts. Kanonnikoff1 has also determined a few atomic refractions. His results, which do not differ much from those of Gladstone, are given on the next page. 1 J.f. pr. Oh. (2), 31, p. 339. The periodicity of the atomic refractions is unmistakable, the maxima falling on the elements of the fifth series, except in the case of arsenic. It is difficult to localise the minimum elements. They hover between groups seven, eight, one and two. Obviously, when we get better data, we shall arrive at more uniform results. The Spectra of the Elements. The study of spectra is of the utmost importance to the physical chemist, for it teaches more about the nature of the atoms than any other property of matter. Owing to the immense amount of work done in the domain of spectrum analysis, it will not be possible here even to give a short sketch of the subject, but only those portions which are of vital importance for our present consideration will be treated of. There are three great classes of spectra:--Emission Spectra, Absorption Spectra, Phosphorescence Spectra. For our purpose we need only consider the first class--Emission spectra. We have here again three great divisions:--(1) Flame spectra; (2) Arc spectra; (3) Spark spectra. The substances giving flame spectra are few in number. They are lithium, sodium, potassium, rubidium, caesium, barium, strontium, calcium, indium, gallium, thallium, boron, and one or two more. The spark spectra are usually employed as all elements give them. For gases this is the only method possible. However, in some cases, the use of the arc spectrum is preferable, e.g., carbon. The spectra obtai...
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