. Annals of the Lyceum of Natural History of New-York. Science. of the Trimetric System. 57 sition, falls into the same group with Orpiment, and is near it in angle. Professor Scacchi, in describing Dimorphine,* recog- nises the fact that it affords two angles approaching those of Orpiment, viz. 83° 40' and 117° 48' ; and he adds correctly, that they do not, however, correspond in position in the two species. But on examining further his type I., and viewing the form in a different position, we find that there are two prisms, which taken as domes give the an- gles at summit 83° 40' and 75° 40'
. Annals of the Lyceum of Natural History of New-York. Science. of the Trimetric System. 57 sition, falls into the same group with Orpiment, and is near it in angle. Professor Scacchi, in describing Dimorphine,* recog- nises the fact that it affords two angles approaching those of Orpiment, viz. 83° 40' and 117° 48' ; and he adds correctly, that they do not, however, correspond in position in the two species. But on examining further his type I., and viewing the form in a different position, we find that there are two prisms, which taken as domes give the an- gles at summit 83° 40' and 75° 40' (an- gles o : o and e : e in Scacchi, pi. 12, f. 4, or 12 and ll in the annexed figure 1); and these angles are so near two domes in Orpiment that we can hardly hesitate as to regarding this the right position for the figures. We here make B of Scacchi the terminal plane 0; A, the plane il; C, the plane il; also o" is ii, and m is 1, or the unit octahedron In Scacchi's type II. (figure 2, above), the planes referred to the same fundamental form, are f* (e of Scacchi, fig. 13, pi. 4), *? C0> f i (w)> ^* (°2)- In tn^s tvPe> tne ang^esj as given in the table, are almost identical with those of Orpiment. The axes become for 5=1 a=l Type I, a : b : c = : 1 : = 1 : : Type II, a : b : c = : 1 : = 1 : : The ratio £ in Type II. loses its improbability, if any there be, when it is observed that the domes of this ratio have approxi- mately the angles of the unit domes of sulphur or of the section to which sulphur belongs, they being |2 = 62° 12' (e : e, f. 13, of Memorie Geologiche sulla Campania per A. Scacchi, Napoli, 1849, p. 120. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Lyceum of Natural History (New York, N. Y. ). New-York
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