Category: Science - Earth/Agricultural/Farming
The idea underlying this book has been to present the phenomena of crystallography to the general reading public in a manner which can be comprehended by all. In the main the sequence is that of the author’s evening discourse to the British Association at their meeting at Winn...
The idea underlying this book has been to present the phenomena of crystallography to the general reading public in a manner which can be comprehended by all. In the main the se...
2. CHAPTER IIt is a remarkable fact that no definition of life has yet been advanced which will not apply to a crystal with as much veracity as to those obviously animate objects of the ani...
3. CHAPTER IINothing is more remarkable than the great variety of geometrical shapes which the crystals of the same substance, derived from different localities or produced under different c...
4. CHAPTER IIIThe important work of Romé de l’Isle had paved the way for a further and still greater advance which we owe to the University of Paris, for its Professor of the Humanities, the...
5. Chapter V., is that the relative lengths intercepted along the threeprincipal axes of the crystal, by the various faces other than those of the fundamental form, the faces of which are parallel to the axes, are expressed by the simplest unit int...
6. CHAPTER IVIt is truly curious how frequently the perfect number, seven, is endowed with exceptional importance with regard to natural phenomena. The seven orders of spectra, the seven not...
7. CHAPTER VThe most wonderful of all the laws relating to crystals is the one already briefly referred to which limits and regulates the possible positions of faces, within the lines of sy...
8. CHAPTER VIIt will have been clear from the facts related in the previous chapters that the salient property possessed by all crystals, when ideal development is permitted by the circumsta...
9. CHAPTER VIIDuring the height of the French Revolution, which caused the work of the Abbe Haüy to be suspended for a time, although he was fortunately not one of the many scientific victims...
10. CHAPTER VIIIIt has been shown in the last chapter how Mitscherlich discovered the principle of isomorphism, as applying to the cases of substances so closely related that their interchangea...
11. Chapter X. we may conclude this chapter by referring first to oneimportant investigation in which the necessity for extreme accuracy of measurement and perfection of material was fully appreciated. This was an admirable research carried out i...
12. CHAPTER IXThe interval between the morphotropic work described in the last chapter and the present time has been remarkable for the completion of the geometrical and mathematical investig...
13. CHAPTER XWe are now in a position to approach the conclusion of the long controversy as to the constancy or otherwise of crystal angles in the cases of greatest similarity, those of isom...
14. CHAPTER XI_Polymorphism._ It has been shown in Chapter VII. that Mitscherlich had in several instances proved the possibility of the occurrence of the same substance in two different form...
15. CHAPTER XIIThe action of transparent crystals on the rays of light which they transmit is a subject not only of the deepest interest, but also of the utmost importance. For it is immediate...
16. Chapter VII., is an excellent substance to employ for the demonstrationof this fact, by cutting and polishing a 60°-prism out of a clear transparent crystal of the mineral as above described; and if a Nicol prism be introduced in the path of the ra...
17. CHAPTER XIIIIt has already been shown that crystals are optically divisible into two classes characterised respectively by single and by double refraction. Singly refractive crystals belong...
18. Chapter VII., of exhibiting the crossing of the optic axial plane in thecase of gypsum, and the production of all the types of interference figures in succession, as the crystal becomes warmed by the heat rays accompanying the beam of convergent lig...
19. CHAPTER XIVIn order to rearrange the projection polariscope for experiments in parallel light, we simply remove the three lenses on separate stands (Fig. 71), and the convergent systems of...
20. CHAPTER XVOne of the most deeply interesting aspects of a crystal, especially from the point of view of the history of crystallographic investigation, concerns the mysterious process of i...
21. CHAPTER XVIWe have seen in the foregoing pages that a crystal is usually a solid, highly organised in a homogeneous manner, and, unless the symmetry be developed to its highest extent, the...
22. CHAPTER XVIINothing in connection with the subject of crystallography is more surprising than the neglect and apathy with which it has been for long treated by the chemical world. That crys...
23. Chapter IX. the important contribution of Mr Barlow to the completion ofthe theory of the homogeneous partitioning of space has likewise been discussed. In collaboration these two investigators have now propounded a theory which connects the chemica...
24. Chapter X. to afford the relative dimensions of the unit cell of thespace-lattice, and the distances of separation of the centres of gravity of the molecules from each other along the directions of the crystal axes, Pope and Barlow arrive at new...
25. Chapter VIII., and of others which are still less intimately connected.Unfortunately, the equivalence parameters do not make clear the relationships in an isomorphous series, as do the molecular distance ratios; for they are, from their very nature...