264 Mr. Griffiths on the Action of Water upon Glass. 



by the action of water, aided perhaps originally by a cer- 

 tain degree of heat, and afterwards by the long period of 

 their continuance, in a situation favourable to the decomposing 

 agency. 



In contact with ammoniacal, or decomposing animal matter, 

 the disintegration of glass takes place more rapidly. Stable- 

 windows, and bottles kept in such situations, often present a very 

 beautiful iridescent appearance, in consequence of the siliceous 

 matter being developed in thin plates on its surface, often amount- 

 ing to a pearly, and sometimes almost metallic appearance; an 

 effect which, it is believed, has not been hitherto investigated. 



Solution of potash acts very rapidly upon glass, as the chemist 

 often inconveniently learns by the effect produced upon the bulb 

 of a thermometer, employed to determine its boiling point, and 

 which is always found corroded to a considerable extent after the 

 experiment. 



It may also here be remarked (although not perhaps imme- 

 diately connected with the subject), that from frequent observa- 

 tions by a person in the habit of using solid carbonate of ammonia, 

 that the flint-glass bottles in which it has been for some time kept 

 are invariably rendered much more brittle, and pieces of glass 

 fall out upon very slight motion of its contents. This fact is 

 merely mentioned as curious, and may probably be hereafter more 

 fully examined. 



Art. V. — Analyses of two Mineral Waters from Springs in 

 Windsor Great Park. By W. T. Brande, F. R. S., Prof. 

 Chem. R. I. 



These waters were sent to me about a twelvemonth ago for ana- 

 lysis, and as I understand that since that period the springs have 

 been much frequented, an account of their contents may not be 

 unacceptable to those who have derived benefit from their use. 



In taste, these waters exactly resemble each other, though one 

 is manifestly more abundant in saline matter ; their taste is 



