Intelligence and Miscellaneous Articles. 563 



accumulation of quartzose sand beneath the cesspool, also brought 

 up by the sounding-line, was subjected to a washing so as to sepa- 

 rate from it the heaviest portions, when innumerable grains of 

 pyrites were distinguished bristling with crystals, and less than a 

 quarter of a millimetre in diameter. Some of these grains have 

 iregular shapes, and appear to be the debris of coatings unlike those 

 which have just been described ; others are rounded, like miniatures 

 of the nodules of pyrites met with in various beds. 



Further, on attentively inspecting the bricks of a Roman floor 

 of a conduit of mineral water, I recognized pyrites there also. This 

 mineral has been produced in the midst of the lime which envelops 

 each brick, in small cavities, where it appears in globules of a 

 brassy yellow, terminated by crystalline faces ; but these faces are 

 so minute that one could not be sure that they belonged to cubic 

 pyrites and not to marcasite : however, their fine yellow colour and 

 their un changeability render the first supposition the more probable. 



Pyrites of contemporary formation exists in general in amor- 

 phous coatings ; this at Bourbonne is distinguished by its crystal- 

 line state. 



Formation of pyrites in calcareous pisolites at Uamman-3Ieskoutiue, 

 Province of Gonstantine. — The thermal springs of ilamman-Meskou- 

 tine, renowned for their high temperature (95° C), their copious- 

 ness, and for the development and singular form of the incrusta- 

 tions which they continue to build up daily in the shape of cones, 

 have also generated pisolites comparable to the granules of Carls- 

 bad or Tivoli. 



Some of these pisolites are enveloped in pyrites. Nor is this de- 

 posit merely superficial : when a number of the globules are broken, 

 in some of them pellicles of pyrites are perceived among the whitish 

 very thin concentric layers of which they are composed. The centre 

 is ordinarily a fragment of crystalline and lamellar limestone which 

 has served as a nucleus for the concretions. 



From information for wmich I am indebted to the kindness of M. 

 Tissot, Mining Engineer, it appears that these pyritous pisolites, 

 which are rare, se?m to be formed in the ascending channels of 

 the thermal springs ; they are therefore brought to light by the 

 force of the ascending water, nearly in the same manner as the 

 pyritous grains of Bourbonne-les-Bains. Although formed at an 

 elevated temperature, the carbonate of lime which accompanies 

 them is in the state of calcite, and not of aragonite ; for it does not 

 decrepitate before the blowpipe. 



Pij rites formed in ivood immersed in sea-water. — The third instance 

 of present formation of pyrites which I have to describe does not 

 belong to the action of thermal springs, but to that of sea-water 

 mingled with fresh water. 



This pyrites was met with recently in England, in the interior of 

 a piece of wood from the royal yacht ' Osborne.' It forms, in a 

 fissure of the wood, a thin coating of a fine vellow colour and bright 



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