68 MEMOIRS NATIONAL ACADEMY OF SCIENCES, VOL. XIII. 



specific gravity, according to Shepard, is 3.116; according to Sartorius, 3.039. Before the blowpipe shepardite fuses 

 only on the edges to a white enamel; in the form of a powder it dissolves easily to a clear glass. In salt of phos- 

 phorus pieces of the mineral are slightly fusible, but in powder it easily forms a glass which, though it contains a 

 skeleton of silica, is transparent as long as it is hot. On cooling, it opalizes. It is attacked with difficulty by hothydro- 

 chloric acid. This is true also of the round grains which Shepard considered to be anorthite. On powdering finely 

 and boiling a long time with hydrochloric acid a diluted and filtered solution gives with ammonia after some time 

 brownish flakes. If I investigated grains of the same kind as Shepard, this can not be anorthite. 

 The chemical composition of the shepardite according to the three analyses is as follows: 



Shepard. 



Magnesia 28. 25 



Lime 



Soda 1. 39 



Potash 



Manganese oxide 



Alumina 



Iron oxide 



Silica 70. 41 



Water 



100. 95 99. 93 99. 79 



According to Shepard, the shepardite, except for a small quantity of soda, is a mixture of silica and magnesia. 

 Shepard alone found no aluminum, probably because he used only the purest crystals for analysis. He also had a 

 larger quantity than the other chemists, who had only small pieces. Shepardite has also the same constituents as 

 olivine in different quantity. It has oxide of magnesia in proportion to silica as 1 to 3, while in olivine it is 1 to 1. 

 It has the calculated composition — 



Magnesia 30. 2 



Silica 69. 8 



Sartorius, thinking that he had a mixture, concluded that the alumina found was from labradorite. From this 

 he reckons a mixture of 5 per cent of the latter. Deducting this, he obtains a formula for shepardite. This does not 

 seem to me warranted, for labradorite of such composition is not known, and no crystals of this form can be recognized. 

 In the chladnite a mixture of anorthite seems more probable, but this is not certain. Rammelsberg first digested 

 the fine powder with concentrated warm hydrochloric acid, and then treated the residue with sodium carbonate. The 

 acid only dissolved 7.55 per cent, indicating only a partial decomposition of the shepardite. He was also convinced 

 that he was treating with a mixture, from the fact that he separated a considerable quantity of the powder of the white 

 crystals by sliming, and analyzed the lightest and heaviest. In this he found some differences of composition. He 

 concluded, therefore, that no formula could be established for the composition of the whole. Although it can not be 

 doubted that chladnite is a mineral species, it is also probable that another alumina-bearing mineral is contained 

 with it. The other ingredients are as follows: 



(1) Nickel-iron, partly in the groundmass and partly in and between the white crystals in small quantity in small 

 grains. They have, according to Shepard, at times the size of a pea. In the piece in the Berlin collection I observed 

 many pieces not much smaller. The iron is always covered with iron oxide, and this has colored the surrounding 

 mass brown more strongly than is usual in meteorites. On scraping the larger grains with a knife, however, the 

 metallic, light, steel-gray color of nickel-iron can be recognized. 



(2) Iron sulphide occurs in small grains rarely. 



(3) There occurs also a black mineral called by Shepard chromium sulphide. He named it schreibersite for 

 Schreiber. This Haidinger changed to shepardite. When the mineral is more completely determined, a new name 

 should be given it. It occurs in small grains or small veins which penetrate the chladnite, and, according to Shepard, 

 also in small prismatic crystals striated on the sides and showing traces of cleavage faces. The mineral has an imper- 

 fect metallic luster, is opaque, and has the hardness of fluorspar. Before the blowpipe it melts with difficulty to a 

 thick glass, and when heated in the crucible it gives a sublimate of sulphur. With borax and salt of phosphorus it 

 forms a green glass. The color is shown strongly, but stronger in the borax glass than in the phosphorus glass, and 

 especially by fusion in the flame and after the addition of tin. 



Smith 7 in 1864 reported a study of the meteorite as follows: 



Several years after this examination (Shepard 's), a fragment of this meteoric stone came into my possession, and, 

 separating a small portion of the mineral in question, it was examined. The result of this incomplete examination 

 justified the statement in a note to a memoir of mine on meteorites, presented to the American Scientific Association 

 in April, 1854, and published in the American Journal of Science for March, 1855, "that from some investigations just 

 made, chladnite is likely to prove a pyroxene." 



Since that announcement I have been placed in possession of other fragments of the meteorite, and have been able 

 to separate the "chladnite" perfectly pure, and in sufficient quantity to submit it to a thorough analysis. 



