Curiosities of Science. 25 



of an exceedingly large size. A crystal of quartz at Milan is 

 three feet and a quarter long, and five feet and a half in cir- 

 cumference : its weight is 870 pounds. Beryls have been found 

 in New Hampshire measuring four feet in length. Dana. 



VISIBLE CRYSTALLISATION. 



Professor Tyndall, in a lecture delivered by him at the Royal 

 Institution, London, on the properties of Ice, gave the following 

 interesting illustration of crystalline force. By perfectly clean- 

 ing a piece of glass, and placing on it a film of a solution of chlor- 

 ide of ammonium or sal ammoniac, the action of crystallisation 

 was shown to the whole audience. The glass slide was placed 

 in a microscope, and the electric light passing through it was 

 concentrated on a white disc. The image of the crystals, as 

 they started into existence, and shot across the disc in exqui- 

 site arborescent and symmetrical forms, excited the admira- 

 tion of every one. The lecturer explained that the heat, causing 

 the film of moisture to evaporate, brought the particles of salt 

 sufficiently near to exercise the crystalline force, the result 

 being the beautiful structure built up with such marvellous 

 rapidity. 



UNION OF MINERALOGY AND GEOMETRY. 



It is a peculiar characteristic of minerals, that while plants 

 and animals differ in various regions of the earth, mineral matter 

 of the same character may be discovered in any part of the world, 

 at the Equator or towards the Poles ; at the summit of the 

 loftiest mountains, and in works far beneath the level of the 

 sea. The granite of Australia does not necessarily differ from 

 that of the British islands ; and ores of the same metals (the 

 proper geological conditions prevailing) may be found of the 

 same general character in ail regions. Climate and geographi- 

 cal position have no influence on the composition of mineral 

 substances. 



This uniformity may, in some measure, have induced philo- 

 sophers to seek its extension to the forms of crystallography. 

 About 1760 (says Mr, Buckle, in his History of Civilization), 

 Rome de Lisle set the first example of studying crystals, ac- 

 cording to a scheme so large as to include all the varieties of 

 their primary forms, and to account for their irregularities and 

 the apparent caprice with which they were arranged. In this 

 investigation he was guided by the fundamental assumption, 

 that what is called an irregularity is in truth perfectly regular, 

 and that the operations of nature are invariable. Haiiy ap- 

 plied this great idea to the almost innumerable forms in which 

 minerals crystallise. He thus achieved a complete union be- 

 tween mineralogy and geometry ; and, bringing the laws of space 



