378 Miscellanies. 



rently from tlie formation of a sparingly soluble iodate ; and when 

 more zinc is added, the liquid becomes milky. No effervescence 

 ensued when iron filings were thrown into the solution of iodic acid, 

 whether concentrated or diluted ; but when the liquid was boiled, a 

 white powder precipitated. 



The solution of the acid reddened litmus paper permanently. 

 The permanency of the color may possibly be owing to a trace of 

 nitric acid still adhering ; as, according to Davy, the acid ultimately 

 bleaches vegetable blues. — Edin. JYew Phil. Jour. June, 1831. 



MECHANICAL PHILOSOPHY. 



I. Influence of Electricity in communicating phosphorescence and 

 color ; by T-^iomas J. Pearsall, Chemieal Assistant in the Labora- 

 tory of the Royal Institution. — The numerous experiments of the 

 author, conducted with great perseverance, and detailed with much 

 minuteness, prove that those mineral substances which are phospho- 

 rescent by heat, and which lose this property by exposure to a very 

 high temperature, will have their phosphorescent powers very much 

 increased, and will regain them after ignition, by the agency of ordi- 

 nary electricity. The method generally pursued by the author, was 

 to place the fragments in the cavity of a piece of ivory, into which 

 were inserted two wires, and to pass regulated discharges through 

 them from a Leyden jar of about two square feet of coated surface. 



Various substances which w'ere not known to be phosphorescent, 

 had the power conferred upon them by the electric discharge, — 

 Among these were statuary marble, calcined ivory, calcined mother 

 of pearl, calcined oyster shells, calcined cuttle-fish bone, calcined 

 scollop shells, chalk, and common egg shells. Some of these exhib- 

 ited by heat, after electrization, light and color of exquisite delicacy. 



The finest effects were from different varieties of fluor, the phos- 

 phorescence of which was immediately restored, and the natural pow- 

 er exalted by electricity. Several varieties exhibited a light equal 

 to the finest chlorophane. 



Some of the substances were heated and electrified above fifteen 

 times, (the shocks and temperature being very variable and intense) 

 without any deterioration of the phosphoric light-. 



The number of electrical discharges requisite to restore phospho- 

 rescence, varies in different substances. In the green fluor from 

 Cumberland, a single discharge enabled the specimen to shine with 



