216 ANNUAL OF SCIENTIFIC DISCOVERY. 



ter. They consist of two prisms, having a length of about 4 

 inches ; their section is that of a trapezium, with a height of half 

 an inch, and with bases respectively half an inch and three-quar- 

 ters of an inch in breadth. It is well known that sulphate of 

 zinc, or white vitriol, may be prepared either by dissolving the 

 metal in sulphuric acid, or, more economically, by roasting the 

 native sulphide or blende, which, by absorbing oxygen during the 

 progress, becomes in a great measure converted into a sulphate 

 of the oxide. When the former method is employed as it gen- 

 erally is on a small scale, and in the laboratory a compound 

 precipitate is obtained containing traces of indium. M. Richter 

 is the first who has succeeded in isolating this metal, and those 

 who know the difficulties attending upon all such experiments 

 can well appreciate the dexterity in manipulation and the skill 

 necessary to accomplish so proud a feat for the chemist as the 

 giving of a new element to the scientific world. The metal bears 

 a great analogy to cadmium, and there is an important fact to be 

 borne in mind respecting the similarity of their properties, more 

 especially when the manner in which indium is produced is taken 

 into consideration. It is that cadmium generally accompanies the 

 ores of zinc. The question that will at once arise is, perhaps 

 after all indium is nothing else than cadmium. Fortunately, how- 

 ever, there is no doubt in the matter. The only oxide which is 

 known formed by indium is insoluble in excess of that substance ; 

 moreover, the spectrum of indium is distinguished by a brilliant 

 indigo ray ; its color, smell, and other properties, somewhat re- 

 semble those of tin, to which cadmium also bears a resemblance, 

 but is rather harder. The two specimens are of exceeding purity, 

 and M. Richter estimated their total value at 800. They were 

 obtained from the Freiberg blendes. 







ITACOLUMITE. A SOURCE OF THE DIAMOND. 



In " Silliman's Journal" for July, 1867, Dr. C. M. Wetherill has 

 published a paper on this subject, from which the following are 

 extracts : 



" The rock which derives its name from the mountain, Itacol- 

 umi, in Brazil, is certainly one of the most interesting with which 

 we are acquainted. As the companion (probably the matrix) of 

 the diamond, a study of its origin and nature might possibly solve 

 the problem of the formation of that gem ; and its flexible charac- 

 ter is at such variance with our ordinary experience of the stabil- 

 ity of rock, that it is wonderful to those even who are most famil- 

 iar with it. 



" According to the authorities, itacolumite is a laminated quartz 

 rock of the talcose series, owing its lamination to a little talc or 

 mica (Dana), to which material its flexibility is also due (Dana, 

 Percy, and others). It occurs in extensive formations in Brazil, 

 the Urals, and in the United States, in Georgia and North Caro- 

 lina, and appears particularly to accompany the diamond. 



"Specimens may be split more readily in one direction, yielding 1 

 slabs, and there are occasionally small fissures at right angles to 



