150 Scientific Intelligence, SfC. 



drous muriatic acid, saturate 312 parts of atropin which gives the 

 atomic weight 240*6. It consists of carbon 70*986, azote 7*519, 

 hydrogen 3*144, oxygen 13*351 ; from which the atom comes out 

 23*45. According to Geiger and Hesse the salts of atropin have a 

 bitter taste, are readily soluble in water and alcohol, less so in ether. 



Muriate of Atropin ^crystallizes in star like needles. When 

 prepared by saturating dry atropin with muriatic acid gas, the salt 

 has an acid re-action, but when crystallized an alkaline re-action. 



Sulphate of Atropin crystallizes readily. 



Nitrate of Atropin dries into a clear colourless mass : j grain of 

 this salt dissolves in a drachm of water. 



Acetate of Atropin crystallizes in stelliform fine needles which 

 lose their acetic acid when completely dried, and are no longer com- 

 pletely soluble in water. 



Tartrate of Atropin forms a transparent colourless mass. 



The discovery of atropin is a very important one, because it is to 

 this substance that the extract of Belladonna owes its peculiar pro- 

 perties in a medical point of view ; 1 part of a salt of atropin is equi- 

 valent to 200 parts of extract or 600 of the dried plant. 



This alkaloid appears to have been first discovered by Mein in 

 1831. He prepared it by digesting the bruised root of Belladonna 

 in alcohol in the proportion of 24 parts root to 60 alcohol, of 90 per 

 cent. The clear solution was digested with slaked lime and filtered, 

 sulphuric acid was then added which precipitated gypsum. The 

 acid solution was distilled to more than one half, mixed with 6 or 8 

 parts of water and the alcohol evaporated. The remaining solution 

 was mixed with a little carbonate of potash, which at first precipitated 

 a resinous matter forming a gelatinous mass, when more atropin was 

 precipitated by the addition of carbonate of potash. In from 12 to 

 24 hours it exhibits a disposition to crystallize, and can then be sepa- 

 rated from the mother liquor and pressed ; it is then soluble in alco- 

 hol and crystallizes by spontaneous evaporation. By a new analysis 

 made by Liebig, the formula for atropin isC34 H^s 1^2 qs and its 

 atomic weight 289*0. (Jahreshericht, 1834, 262.J 



II. — Phenomena of Crystallization. 



When the formation of crystals are observed under the microscope 

 according to Ehrenberg, the first thing which attracts attention is 

 a rapid action going on about the crystal ; suddenly a solid point forms 

 in the transparent liquid, appreciable by its opalescence, and increases 

 with astonishing rapidity, shewing that this point concentrates and 

 condenses the saline particles previously dispersed and suspended 

 in the water. This concentration supposes a motion towards the 

 centre, and one is apt to think that the agregation of the atoms is of 

 such a nature that the density will increase towards the edge. In this 

 view it is rather surprising that there should be no motion nor agita- 

 tion in the neighbourhood of the crystal. In order to investigate 

 the subject more accurately, Ehrenberg examined strongly coloured 

 crystals. He dissolved bichromate of potash and sulphate of copper 

 in water : he could not discover in either case any visible current re- 



