108 MEMOIRS NATIONAL ACADEMY OF SCIENCES, VOL. XIII. 



the central skeleton we find a half-blended secondary skeleton near the border of the field, yet divided from this by 

 plessite. The secondary laminae are sometimes bunched, but do not run in comb fashion from the border of the field 

 toward the middle. In places where the fields disappear and a coarse band structure prevails, numerous Reichenbach 

 lamella? from 5 to 10 mm. long occur, which consist of lumps of troilite, for the most part composite, seldom individual, 

 arranged in planes and enveloped in kamacite 0.2 to 0.4 mm. thick. Of rare occurrence are isolated points of cohenite 

 in the lamina;. Huge inclusions of schreibersite, for the most part bordered by crystal facets and inclosed by finely 

 hatched kamacite bands 0.5 to 1 mm. thick, appear, sometimes isolated, sometimes united into groups and bunches, 

 and attaining a length of from 4 to 6 cm., sometimes even from 10 to 12 cm. Round about such a colony of schreibersite 

 crystals the fields predominate in a striking manner. Not infrequently occur troilite grains or crystals, sometimes 

 quite regular in outline, sometimes fresh, sometimes limonitized, mostly 1 to 1.5 cm. in size, with a corona of schrei- 

 bersite crystals from 2 to 8 mm., enveloped in swathing kamacite. Curving of the Widmannstatten figures is frequent 

 on the larger cavities of the exterior. The curving follows the cavity like an onion skin along the octahedral laminae 

 and transverse cracks between such. 



Cohen 5 made the following additional observations : 



For Carlton change in structure is especially characteristic. Here and there the fields are large and numerous 

 so that the plessite largely predominates; in other parts the plessite varies and bands are in about equal proportions; 

 and finally the latter may be bo predominant that the fields, both in size and number, almost disappear. The bands 

 consist of fine-grained kamacite and are long, straight, and often grouped, in part equal and in part unequal, and the 

 groupings are the more abundant the more the plessite is subordinate; here also the bands seem to be finer. Brezina 

 gives the breadth of the lamellae in cross section as 0.2 mm. The taenite appears in relatively broad ribbons and un- 

 usually sharp, like to Laurens, and adds considerably to the beauty and delicacy of the appearance of the etched sur- 

 face. The plessite is dark gray and compact, homogeneous in the smaller fields, and in the larger sparkling from little 

 shiny taenite flakes which are quite often arranged in zones. With them often appear central skeletons whose inter- 

 growth with the edge of the fields was observed by Brezina. Combs seem to occur quite scatteringly. The richness 

 in great schreibersite crystals is an important feature. On a plate in the Vienna Museum, measuring 300 sq. cm., one 

 sees thirteen groups of crystals some of which reach a length of 4 cm. In a plate figured by Howell the number is 

 smaller but the individuals reach, as stated, a length of 15 cm. From the form of the sections it would appear that 

 the crystals are numerously bounded by faces. The schreibersites are surrounded by swathing kamacite which often 

 attains a considerable breadth, and according to Brezina is not granular like the kamacite in the bands, but finely 

 hatched. In the neighborhood of many crystal groups the structure through the increase in size and number of the 

 fields is coarse-meshed. Troilite occurs sparingly. It appears almost wholly only in short Reichenbach lamellae, 

 which exceptionally reach a length of 5 to 10 mm., and which according to Brezina as a rule are connected, although 

 at times isolated. They are arranged in planes surrounded by the swathing kamacite 0.3 to 0.4 mm. thick and seem to 

 be very unequally distributed. Brezina mentions point-like cohenite occurring rarely in the bands; Farrington troilite 

 in radiated veins; and I observed troilite and graphite in some well-formed crystals. In many places the octahedral 

 lamellae are dislocated. According to Brezina the dislocation follows onionskin-like concavities on the surface along 

 octahedral lamellae and swellings between them. In the neighborhood of the natural surface a strong bending of the 

 lamellae has occurred on one side of the mass, which indicates that the block here struck the earth. Leick determined 

 the specific gravity as 7.8542 at 20.6° C. According to him the iron takes pretty strong permanent magnetism— 

 5.82 — and possesses a specific magnetism of 5.76 absolute units per gram. 



The meteorite is distributed, Vienna possessing 0,986 grams, London 6,185, Ward 5,592, 

 Chicago 3,406. 



BIBLIOGRAPHY. 



1. 1890: Howell. Notice of two new iron meteorites from Hamilton County, Texas, and Puquios, Chili, South 



America. — 1. The Hamilton County Meteorite. Amer. Journ. Sci., 3d ser., vol. 40, pp. 223-224. 



2. 1890: Howell. Description of new meteorites. — The Hamilton County Meteorite. Proc. Rochester Acad. Sci., 



vol. 1, pp. 87-89. 



3. 1893: Meunier. Revision des fers m6teoriques, pp. 65 and 66. 



4. 1895: Brezina. Wiener Sammlung, pp. 270-271. 



5. 1895: Cohen. Meteoreisen-Studien IV. Ann. K. K. Naturhist. Hofmus, Wien, Bd. 10, p. 82, 90. 



6. 1905: Cohen. Meteoritenkunde, Heft 3, pp. 265-268. 



Carroll County. See Eagle Station. 



