§ 



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Fou?^th Supplement to Dana's Mineralogy. 107 



In concluding* for the present an investigation to -wliich \iQ 

 have devoted our leisure for several years, and which has been 

 one of extraordinary difficulty, we desire to state our conviction 

 that the subject is by no means exhausted, but that on the con- 

 trary there is scarcely a single point which will not amply repay 

 a more extended study. The number of bases which the ses- 

 quioxyd of cobalt is capable of forming with ammonia is per- 

 haps very large, and a careful study of the products of the de- 

 composition of the salts of each base promises to yield an abun- 

 dant harvest of interesting combinations. It is our hope to be 

 able to return to the subject hereafter, and in a second part of 

 our memoir to clear up some points which we have not as yet 

 had time and opportunity fully to consider. In the mean time, 

 we invite the attention of chemists to a class of salts which for 

 beauty of form and color, and for abstract theoretical interest, 

 are almost unequalled either among organic or inorganic com- 

 pounds. 



ITew York and Pliiladelphia, July, 1856. 



Art. IX. — Fourth Suppilemeyit to Dana's Minerahgy ; by the 



Author. 



The number of new species and new works in mineralogy 

 which have been announced abroad since the date of the hust 

 Supplement is very small. We count up but three or four new 

 nanies, one work on crystallography and another on artificial 

 minerals, besides reviews and memoirs. Kenngott has issued his 

 annual review '* Uebersicht," etc. for the years 1854 and 1855, 

 each a small quarto of 180 pages, posting up, in detail, whatever 

 relates to the composition of rocks and mineral springs, as well 

 as minerals. The annual published in Liebig's Jahresbericht for 

 1855, covering the same ground, has also appeared, having been 

 prepared by Dr. Kopp. 



In this country we have had some additions to the new names, 

 and nearly all by Prof. C. U. Shepard. Professor Shepard has 

 also issued the second (and concluding) part of his Treatise on 

 Mineralogy, the first part of which appeared in 1852, Dr. 

 Genth also has contributed an important paper to this Journal 

 on American minerals. 



The anhydrous silicates fall mainly [see Mineralogy] into two 

 large groups, the Augite and Qarnct sections — the former having 



* I should do no justice to ray own feeliags if I did not in this place gratefully 

 ncknowledge the assistance ■which I have received in the analytical part of the labor 

 from my friend and pupil, Mr. James R. Brant, whose zeal and skill have alone ren- 

 dered it possible for me, amid the duties of a laborious professorship^ to bring mj* 

 own share of the work to a conclusion. — ^. c. 



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