318 Chemical Ohservations upon Spathic Iron. 



white, while that which is made from maillat is generally 

 gray, and yields iron. These two kinds are mixed with 

 advantage in the manufacture of steel. 



Perhaps the specific gravity, the loss by calcination, and 

 the alacrity in changing colour, are better proofs of the com- 

 position than the texture is. This is a conjecture, however, 

 which can only be verified by a great number of analyses 

 upon specimens of different kinds. 



I ought, however, to remark, that the sulphate of magnesia 

 crystallizes nearly similar to the sulphate of zinc, and that 

 this similarity of form probably led Bayen into his mistakes. 

 This chemist, full of the idea that the flakes which he had 

 perceived in the muriatic solution came from the zinc, while 

 they were truly owing to the manganese, must have neglected 

 to examine the crystals he obtained. This opinion is besides 

 confirmed by the details given by M. Dize, upon the pro- 

 perties of the white earth, from which he only obtained a 

 very few particles of zinc by distillation with charcoal. 



It is probably still this same sulphate that M. Sage re- 

 garded as sulphate of manganese. In fact, that of magnesia 

 crystallizes easily enough, and before the sulphate of iron. 



I have made these observations with a view of concluding 

 from them that magnesia is generally found in greater quan- 

 tity in the translucid and well crystallized ore, to which the 

 name of maillat is given in the department of Iserc, and is 

 that also to which the chemists who have been occupied 

 with this substance have given the preference as the purest. 

 The specimen described and analysed by M. Bucholz seems, 

 however, to be an exception to this rule, and I ought to 

 mention it. 



Almost all mineralogists regard spathic iron as the most 

 fusible ore of iron, and, in fact, in several countries it is 

 very fusible ; but it does not appear that it is every where 

 very easy to melt ; and if we reflect on the processes in use 

 in the founJcries in which this metal is wrought, we must 

 know that there are but few manufacturers who do not em- 

 ploy additions of different kinds, or particular preparations, 

 for the purpose of rendering it more easily fusible. In some 

 founderies they add to it carbonate of lime ; which shows 

 2 that 



