550 SCIENTIFIC RECORD FOR 1884. 



1884, II, 19 ref.) good crystals of andesiue from Orijjirvi in Finland. 

 J. H. Kloos has contributed [Jalirh. Min., 1884, ii, 87) a series of optical 

 observations on orthoclase and microcline. He concludes that the two 

 species are thoroughly distinct, orthoclase being strictly monoclinic and 

 microcline triclinic, although the latter by very fine tvvinning may imi- 

 tate the monoclinic mineral. He does not support the view which has 

 been advanced that orthoclase is nothing but a mimetic microcline. The 

 observations of Forstner (see above) bear upon this subject. 



Of researches bearing upon the cohesion in crystallized substances two 

 new papers by Miigge must be referred to {Jahrh. Min., 1884, i, 50, 216). 

 Becke discusses at length the etching-figures on galena (Min Fetr 

 Mitth., VI, 237). 



CHEMICAL MINERALOGY. 



Of contributions to the general subject of chemical mineralogy several 

 papers by Eammelsberg deserve to be mentioned first. These are de- 

 voted to the discussion of some points bearing on the isomorphism of 

 minerals {Jahrb. Min., 1884, ii, 67) ; on the chemical relations of the 

 natural borates {lb., p. 158). Blomstrand discusses {Geol. For. Forh., 

 Stockholm, vii, 59) the composition of the native compounds of uranium' 

 AnimportantpaperbyDoelterand Hussak {JaJirh. Min., 1884,1,18) deals 

 with the action of a melted rock upon different minerals, with a view to 

 throwing light upon the contact phenomena observed in nature. Fine 

 pulverized rock, as basalt, andesite, or phonolite, was melted in a por- 

 celain crucible, and then the mineral to be experimented ui)on was in- 

 serted into the molten mass. The minerals chosen for the experiment 

 were pyroxene, hornblende, biotite, feldspar, olivine, quartz, garnet, 

 iolite, and zircon. The results of the experiments are not without in- 

 terest, though of too special a character to be detailed here ; they do 

 not lead to any broad conclusions. Another paper {Ih., p. 158) by the 

 same authors describes the results of trials with different varieties of 

 garnet and vesuvianite, tkese minerals being fused and the products 

 resulting from the recrystallization of the melted material studied. For 

 example, melanite yielded in this way meionite, anorthite, and a variety 

 of olivine ; grossularite, from Wilui, gave meionite, a little anorthite, a 

 mineral like melilite and perhaps hematite, and so on. The original 

 mineral was not reproduced, and, moreover, the fusing together of ne- 

 phelite and augite, and alsoof meionite and olivine, failed to yield garnet. 

 Doelter has also made an interesting series of synthetic experiments 

 {lb. II, p. 51, Zeitsch. Kryst., ix, 321) on the pyroxenes and nephelite, 

 the results of which deserve to be studied in detail. 



In the line of chemical studies of individual mineral species, Pen- 

 field's paper on the composition of beryl {Amer. Jour. Scl, xxviii, 25) 

 is perhaps the most interesting. The formula of beryl, as previously ac- 

 cepted, was that of a simple bisilicate of aluminum and beryllium, and 

 the only uncertainty surrounding it was supposed to be that connected 



