On the Colouring of Glass by Metallic Oxides. 439 



posite to the true sun ; also a mock sun, G, situated 4° below 

 the apex of the circle, BB, on the left-hand side. 



0^ 33". The winged appearance is the only portion which 

 now remains. 



0^ 39™. AA has just vanished. 



During the whole of this phaenomenon thin scud was flying 

 rapidly over from the south, and the sky itself appeared of a 

 muddy blue, owing to a thin veil of vapour (probably cirro- 

 stratus) being interposed between us and the clear sky. Whilst 

 this singular appearance lasted, a thin sprinkling of rain con- 

 stantly fell. The sky became overcast at 0^ 45"^ with south 

 wind. Brilliant aurora borealis in the evening. 



Villa, Beeston near Nottingham, 

 October 23, 1849. 



LIV, Inquiries oji some modijications in the Colouring of 

 Glass by Metallic Oxides. By G. Bontemps*. 



IN the presence of so many illustrious philosophers to 

 whom the sciences are so much indebted, I must certainly 

 apologize for my temerity in daring to call for a few minutes 

 their attention to my humble observations ; but if it is true 

 that the greater part of the improvements in manufactures are 

 the consequences of new scientific applications, it will be per- 

 haps admitted that the observation of facts connected with 

 manufactures has led to many new scientific discoveries ; and 

 I should feel happy if I could bring before you a few elements 

 of new progress. 



The revival of painted windows, and the manufacture of 

 coloured flint-glass, first in Bohemia, and afterwards in all 

 parts of Germany, in France and in England t» in an especial 

 manner directed the attention of glass manufacturers, about 

 fifteen years ago, to the colouring of glass by metallic oxides. 

 They probably tried the receipts described in the works of 

 Neri, Merret, Kunckel, Ferrand, Haudiquer de Blancourt, and 

 many others, and they must frequently have met with failure; in 

 that case their conclusion must have been,that the authors did 

 not obtain the results which they announced. But the truth is, 

 that they had not opei'ated under like circumstances. In all cases 

 those receipts had but an empirical value ; chemistry was not 

 yet a science; it was merely an agglomeration of facts without 

 any co-ordination whatever ; nor was natural philosophy better 



* Communicated by the Author, having been read before the British 

 Association at Birmingham, Sept. 1849. 

 f See Phil. Mag., vol. ix. p. 456. 



