ON STONY" AND METALLINE SUBSTANCES. \5% 



Thirdly, That feveral of thefe colours change likewife upon 

 the glafs by becoming perfectly tranfparent, particularly the 

 yellows and violets. 



Fourthly, That neither an additional calcination, nor a pre- 

 vious fufion, as has been fufpecled, will prevent them from 

 changing. For this method alters the colours that change, 

 and does nothing to the reft. The change which feveral co- 

 lours undergo on tender porcelain and on glafs, does not 

 therefore relate to the nature of their compofition, but rather 

 to that of the body on which they are placed. 



Confequently by fuppreffing the carmine of gold from the 

 colours of hard porcelain, we (hall have a feries of unchange- ' > 



able colours, which would be abfolutely fimilar to thofe pre- 

 fented to the Inftitute in the year 6 *. 



IV. 



Experiments and Obfervations on certain fiony and metalline 

 Subjlances, which at different Times are /aid to hate fallen 

 on the Earth ; alfo on various Kinds of native Iron. By 

 Edward Howard, Efq. F. R. S. From the Philojbphical 

 TranfaBions, 1802. 



(Concluded from Page 101 J 



Defcription of various Kinds of native Iron. . By the Count de 

 Bournon. 



JL HE great number of particles of iron, in a perfectly me- Remarks on the 

 tallic ftate, contained in the ftone from Bohemia, and the faid manner in which 

 particles being fo near each other, naturally lead to fome re- have been 1 **** 

 flections reflecting the exiftence of native iron, which, by formed, 

 many mineralogifis, is fiill confidered as problematical. Let 

 us fuppofe for a moment, that thefe particles of iron were to 



* The preparation of colours for lively grounds by ftrong fire is 

 under the care of Cit. Chanon, and that of the colours for painting 

 to Cit. Meraud already quoted. It is to their care and intelligence 

 in this chemical art, that the manufacture of Sevres is indebted for 

 the prefervation of its beautiful colours, which they have very much 

 varied and improved. ---B. 



approach 



