Chemical Observations upon Spathic Iron. 319 



that lime is not very abundant in the great masses : in 

 others, argillaceous ores are added, and also carbonate of 

 lime. If, besides, we compare the melted produce with the 

 charcoal necessary, we find that this ore requires a consi- 

 derable quantity of fuel. My colleague, M. Le Livec, en- 

 gineer of the mines in the departments of Mont Blanc and 

 Leyman, who has made upon this substance very numerous 

 experiments in the department of Mont Blanc, is convinced 

 that, in order to obtain one part of metal, two, three, and 

 even four parts of charcoal are necessary. Besides, the 

 scoriae always contain globules of metal like small shot: this 

 happens with all ores of difficult fusion. 



In some establishments it is found advantageous to expose 

 the ore to the extremes of the atmosphere during a space of 

 time more or less considerable. In some works this expo- 

 sure takes place after roasting ; in others, before and after ; 

 and lastly, in some, at the iron-works in Styria for instance, 

 they content themselves with exposure, and do not roast the 

 ore at all. They deposit at the opening of the galleries the ore 

 in beds or in large layers, and leave it exposed to the rain and 

 snow for a long space of time. In a memoir upon the forges 

 of this country, M. Rambourg relates that this exposure con- 

 tinues sometimes fifty or sixty years. In Mont Blanc some 

 forge-masters keep the heaps of roasted mineral always humid 

 by means of a very small stream of water. It has been ob- 

 served that these different preparations render the mineral 

 much more fusible ; and nevertheless in some iron-works 

 the necessity is still felt sometimes of mixing with the above 

 mineral * a certain quantity of the ore called by the work- 

 men mild ore, and which comes from the decomposition of 

 the spathic iron, occasioned by a very long action of the air 

 and humidity. In this state the ore, which was formerly 



* M. Hcricart de Thury, engineer of the mines, in a report to the prefect 

 of the department of lsere, says, in speaking of the veins of the Vaunaveys 

 mountains at Visilles : " White or yellowish translucid carbonated iron is the 

 most abundant. When it has been extracted, it is left some time in the open 

 air to asbiu its decomposition, and after roasting they expose it again to the at- 

 mosphere to render it more easily fusible. In spite of these precaution) thry 

 are still often obliged to mix it with mild ores (mch ores as are entirely dc- 

 coinpoted)i lorqfractttry it this spathic ore" 



rei'ractor\', 



