72, Dr. Mac Culloch on Jasper. 



The ornamental appearance is often produced by the veins ; 

 and, as these become numerous in proportion to the base, it 

 forms brecciated jaspers. The colours are much varied, but red 

 and yellow, with white or colourless veins, are the most common.. 

 Sicily appears to abound in the most beautiful specimens of this 

 variety. 



E. Minutely columnar, and resembling, except in hardness, the 



columnar ironstones. Found in the Isle of Man. 



F. With a conchoidal fracture and resinous lustre : pseudo- 



pitchsfones. 



These have been generally enumerated among the pitchstones, 

 as already remarked, and as the colours have been considered 

 important, they are here made a ground for distinguishing the 

 subvarieties. 



a. Pale yellow. 



b. Ochre yellow. 



c. Brick red. 



d. Brown and purple brown. 



e. Green. 



/. Mottled with different colours. 



The green variety is coloured by chlorite, and occurs in 

 Iceland. They all pass into clay, and the transition is often found 

 even in hard specimens. They appear to occur in volcanic, as 

 well as in trap, countries. St. Helena and St. Vincent produce 

 examples of this nature. 



Some of the jaspers appear to pass into common opal, as 

 they do into agate. 



Art. IX. A Translation o/'Rey's Essays on the Calcinatmi 

 of Metals, &^c. 



[Communicated by John George Children, Esq., F.R.S., &c.] 



The original edition of Key's Essays, of which there is a copy in the 

 library of the British Museum, was published at Bazas, a town about 

 thirty miles S.E. of Bourdeaux, in the year 1630. In 1777, it was re- 



