66 MEMOIRS NATIONAL ACADEMY OF SCIENCES, VOL. XIII. 



After Shepard, Sartorius von Waltershausen interested himself in this white mineral. The former observed thereon 

 single crystals, sometimes at most an inch in size, whose form resembled in general that of feldspar but whose faces were 

 rough, unfit for measuring. Two fracture planes are easily distinguished. Sartorius found the chladnite similar to 

 wollastonite and speaks of two and one branched, although microscopic, crystals. The specific gravity is, according 

 to him, 3.039, and according to Shepard, 3.116. 



The composition of the so-called chladnite as given by both the above is very peculiar. 



Shepard. Sartorius. 



Silicic acid 70.41 67.14 



Alumina 1. 48 



Iron protoxide 1. 70 



Magnesia 28.25 27.12 



Lime 1. 82 



Sodium L 39 



Water 67 



100. 05 99. 93 



If the above bases of the magnesia be added the whole would have the composition magnesia-trisilicate, a combi- 

 nation not hitherto known among minerals. The nearest to it is a mineral investigated a long time ago by Stromeyer, 

 which is said to resemble olivine and to be contained in an alleged iron mass found near Grimma, but this substance 

 is basic and contains essential iron protoxide. 



Silicic acid 6L 88 



Magnesia 25. 83 



Iron protoxide ,- 9. 12 



Manganese protoxide 31 



Chromic oxide 33 



Loss by heating 45 



97.92 



Stromeyer's conjecture, that it was a trisilicate, is not correct, since the proportion of oxygen of the base and the 

 acid is l:-2.6, from which, assuming 1: 2.5, the composition may be expressed by 2MgSi+Mg 2 Si 8 or SMgSi+MgSi-j. 

 It is to be regretted that nothing more definite concerning this mineral is known. 



The conjecture of Sartorius von Waltershausen that 5 per cent of a sodium-free labradorite is included, to which 

 he relates the alumina, seems to be unfounded. 



Through the kindness of G. Rose and Dr. Homes, of Vienna, I obtained a sufficient amount of the rare material to 

 undertake some experiments with the principal mass of the Bishopville stone. I observed no signs of crystalline 

 structure, except indeed the ready cleavage of the, for the most part, extremely pliable and friable mass. The colored 

 portions of the crust and the yellowish-brown and bluish-green particles of the interior of the mass are very well dis- 

 tinguished. The former appeared as if produced by the weathering of iron sulphide or by the oxidation of iron. In 

 fact, a few metallic particles were isolated with the magnet, but these were much too little for further examination. 

 Shepard also stated that the stone contained, here and there, small grains of nickel-iron much rusted, as well as a small 

 amount of brown iron sulphide. 



I first treated the fine powder from the stone with concentrated hydrochloric acid and heated the undissolved 

 portion with a solution of carbonate of soda. There remained a residue of 90.75 per cent, while the decomposed por- 

 tion consisted of 



Silicic acid 2.29 



Iron oxide - 97 



Manganese protoxide 20 



Magnesia 3. 51 



Lime.*. 58 



7.55 



Thereto must be added 0.8 per cent of moisture, and possibly also some alkali. What the acid dissolved is evi- 

 dently no unusual compound, but a mixture of oxide of iron (or rather hydrate) and the principal mass, the silicic 

 acid of which could not be completely separated from the unaffected portion. 



This latter was divided into two portions and dissolved with carbonate of soda as well as hydrofluoric acid, after 

 which 100 parts of the mass contained: 



Silicic acid 60. 86 



Alumina 3. 00 



Iron oxide 31 



Magnesia 34. 48 



Lime 11 



Sodium 1. 26 



Potash 93 



100.95 



