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vestigation, was a yellow amorphous substance, found in very 

 small quantity, which gave off water in the closed tube, became 

 milk-white before the blowpipe, and, with the strongest heat, 

 melted at the edges into a white enamel ; with microcosmic salt, 

 gave a colorless bead, and became blue with nitrate of cobalt. 

 As these characters agreed with those of the Damourite above, 

 he made several trials with reagents, and found it to be a pure 

 silicate of alumina, with a small percentage hydrate of potash. 

 He sent a portion of it to Mr. A. A. Hayes, of Roxbury, who was 

 kind enough to repeat the examination, with the same result. It 

 is found in recesses of the albite, at the tourmaline locality, and 

 appears to have undergone severe pressure. 



In the Kyanite from Leiperville, Pennsylvania, there is also a 

 yellow substance which attracted the attention of Mr. T., two or 

 three years ago. Like the Damourite, it is pressed so hard 

 against the Kyanite that it is scarcely possible to separate them 

 from each other. This has also been subjected to the same trials 

 as the other, both by Mr. Hayes and Mr. T., and with the same 

 results. These two minerals are therefore, unquestionably, the 

 Damourite of M. Delesse. The latter, from Leiperville, is found 

 plentifully, although Mr. T. is not fortunate enough to possess suffi- 

 cient for further analysis. The closing remarks of M. Delesse, 

 on the early conditions of the rock in which it is found, as indi- 

 cated by its analysis, are of great interest, both in themselves as 

 well as in exhibiting the importance to geology of considerations 

 on the absolute conditions requisite for the formation of the differ- 

 ent minerals that are interspersed among the various formations. 

 Knowledge on this subject, when more facts are collected and 

 generalized, will, probably, cause considerable change in many 

 of the theories current in the present state of science. 



Mr. T. stated that, by the kindness of Dr. J. W. Webster, a 

 further supply of Pyrrhite, an interesting mineral found in vol- 

 canic ejections at the Azores, has been placed in his hands. He 

 had measured the orange-red octohedrons, which give 109.28', 

 and are therefore, as he had previously supposed, the regular 

 octohedron. There are, however, other crystals, accompanying 

 them, of which the forms are widely different, although, before 

 the blowpipe, they give the same reaction with oxide of titanium as 

 the others. The color of these crystals is also rather of a reddish 



