446 MEMOIRS NATIONAL ACADEMY OF SCIENCES, VOL. XIII. 



Mcunier 23 treated the crust of Toluca with bichloride of mercury, also with very dilute 

 hydrochloric acid, and analyzed the portion removable by magnets with the following result 

 (specific gravity 4.89) : 



Fe 2 3 68. 93 



FeO 28.12 



NiO 2. 00 



CoO trace 



99.05 



The presence of magnetite was thus indicated. 



Rath 2i expressed the opinion that the crystals observed by Krantz were not magnetite. 

 Smith 25 examined the troiUte of Toluca for daubrfielite and found it in marked quantities. 

 He says : 



The residue from 2,800 grams of it, after thorough treatment with chlorhydric acid, which dissolves nearly the 

 whole of it, was dissolved in part by nitric acid, and on analysis the solution was found to contain chromium and iron 

 representing about 60 milligrams of daubreelite. The mineral obtained from these troilites was of the pulverulent 

 variety. 



Smith 26 mentioned the occurrence of nodules (concretions) of troilite, schreibersite, and 

 graphite in the Toluca meteorites; also of compound nodules of which a sufficient quantity could 

 not be obtained for satisfactory examination. 



Brezina, 28 in his 1885 catalogue, described Toluca as follows: 



The Toluca iron shows lamellae 0.9 mm. in breadth and frequently has very numerous large troilite inclusions with 

 or without graphite with which the scaly troilite sometimes alternates. Schreibersite, especially in the vicinity of 

 the troilite, is often well but irregularly developed. 



Ansdell and Dewar 29 tested a nodule of graphite from a Toluca iron for gaseous constituents 

 with the following results (specific gravity, 2.26; occluded gases in volumes of graphite, 7.25): 



C0 2 91.81 



H 2.50 



CH, 5.40 



N 0.10 



99.81 



Flight so gave a photograph of a surface of the Toluca iron etched with bromine water. 

 Castillo 31 gave a list of what he states are "meteorites of one and the same fall found at 

 San Juan de Xiquipilco, in the valley of Toluca." The list is as follows: 



Meteoric iron of Ocotlan, small fragment; meteoric iron of Tenango, small fragment; meteoric iron of Cerro de San- 

 tiago, near the Hacienda de la Gavia, small fragment; meteoric iron of the Sierra de Montealto, District of Xiquipilco, 

 small fragment; meteoric iron of Hacienda de Mafii, District of Ixtlahuaca, small fragment. 



Fletcher 32 gave abstracts of a number of accounts of the Toluca meteorites and regarded 

 all iron meteorites that have been found in the States of Mexico and Morelos as probably be- 

 longing to this fall and artificially transported. He thus included Ameca, Amates, and Cuerna- 

 vaca, which Castillo fisted as separate falls, with Toluca. Later usage, however, follows Cas- 

 tillo in making Amates and Cuernavaca separate falls, Cuernavaca being a fine octahedrite. 



Cohen and Weinschenk 33 made an elaborate investigation of a Toluca iron, as follows: 



A piece weighing 299.4 grams was treated for 14 weeks with 1 part of hydrochloric acid and 20 parts of water, the 

 acid being frequently renewed. During solution the kamacite became covered occasionally with a dark layer which 

 probably consisted of fine particles of separated carbon. The tsenite on the other hand showed, during the whole 

 treatment, no alteration whatever. The process of solution showed a continued development of hydrogen sulphide. 

 After some time a deep hollow formed from which large crystals of schreibersite (about 2.5 grams) fell out. They 

 were gathered at this point in a nested fashion. In their neighborhood the solution of the nickel iron took place con- 

 siderably faster than in other portions of the plate where large schreibersite crystals were completely lacking. In 

 order to facilitate the process of solution the loose tsenite plates were from time to time removed. Occasionally tetra- 

 hedral, or more rarely rhombohedral pieces surrounded by tsenite, were obtained — probably Flight's iron tetrahedrons. 

 These were protected by their tsenite covering from further action of the acid. As a rule, however, the tsenite lamellse 

 separated so that the acids had free access to the kamacite, and finally a residue consisting only of the finest foliae 



