32 



NATURE 



\_Nov. 9, 1 87 1 



to the scales of Kirchhoff's and oi Angstrom's maps. Of the 

 seventy new lines which are given in this list, there are two 

 which are proved to belong to the chromosphere, and not to be 

 due to the exceptional elevation of matter to heights where it 

 does not properly belong. No less than twenty of these lines 

 are due to the metal titanium, and show the presence of titanium 

 vapour in the prominences and chromosphere. 



The cultivation of beet-rcot sugar in France has now risen to 

 an industry of the first importance. It employs more than 400 

 manufactories, and the process of manufacture is each year 

 brought to a higher state of perfection. There are in France 

 three or four journals specially devoted to subjects connected with 

 the manufacture, its cultivation, its sale, the machinery required, 

 the chemistry of the process, &c. 



The Fourth Annual Report is published of the Trustees of 

 the Peabody Museum of American Archaeology and Ethnology 

 at Cambridge, U.S.A. Two important series of explorations 

 have been carried out in the course of the past year on behalf of 

 the Museum, by the Rev. F. O. Dunning in E.is:ern Tennessee, 

 and by Dr. Berendt in Central America, resulting in valuable 

 acquisitions to its collections. The Museum has also been en- 

 riched during the year by the gift of the "Charles Hammond 

 Collection " from the towns of Chatham and Rochester, Cape 

 Cod, and by a very valuable series of about 125 objects from the 

 conservator of the Christy collection in London, consisting of 

 original specimens and casts from Les Eyzies, La Madelaine, and 

 Le Moustier, in the department of Dordogne, France. The 

 Report is accompanied by a set of comparative measureme^its 

 of cranii from Peru, presented by Mr. Squier, of those from 

 the mounds of Kentucky obtained by Mr. Lyon, and from the 

 mounds of Florida. 



The Annual Convcisazionc of the Royal Society of Victoria 

 was held on August 14, when the president, Mr. R. L. J. 

 Ellery, delivered an address, in which he referred especially to 

 the scientific results of theeclipse of last winter, and the prepara- 

 tions making in Australia for observing the eclipse of next 

 month, to Prof Heis's observations on the correspondence of 

 auroral phenomena in the southern and northern hemispheres, 

 to Dr. von Mueller's botanical researches in the colony, to the very 

 important subject, economically, to the colony of the preservation 

 of meat, and to Prof. Tyndall's germ theory of disease. 



The Report is published of the Annual Meeting of the 

 Academy of Sciences of Vienna, held on the 30th of May, 

 1S71, containing a review of the proceedings of the various de- 

 partments of the Academy during the past year. The Academy 

 has also issued its "Almanack," with list of home, foreign, and 

 honorary members. 



A SUPPLEMENT to the Sixth .and Seventh Annual Report of 

 the "Verein fiir Erdkunde " at Dresden, by D. Abendroh, 

 contains a very interesting series of maps, illustrating the extent 

 of geographical knowledge of the world possessed at different 

 periods from a.d. 1350 to 1566. 



A WORK has come out in Holland which particularly in- 

 terests those who are engaged in the treatment of sewage manure. 

 It is by M. J. A. C. Eschauzler, and gives all the results of the 

 centuries of experience in the Netherlands. It is copiously 

 illustrated. 



We are informed that the German translation of Tylor's 

 " Primitive Culture " is not by Dr. Spengel, but conjointly 

 by Herr Spengel and Herr Poske. 



A NRW class for civil engineering has been formed in the 

 Presidency College, Calcutta. 



The Madr.is Government has allowed 200/. for the expense 

 of bringing the Assistant Government Astronomers to England 

 to learn celestial photography. 



THE GEOGNOSY OF THE APPALACHIANS 



AND THE ORIGIN OF CRYSTALLINE 



ROCKS* 



II. 

 'X'HE characteristic examples already given of symmetrical and 

 ■'• asymmetrical envelopment are cited from a great number of 

 others which might have been mentioned. Very many of these are 

 by the pseudomorphists regarded as results of partial alteration" 

 Thus, in the case of associated crystals of andalusite and cyanite, 

 Bischof does not hesitate to maintain the derivation of andalusite 

 from the latter species by an elimination of quartz ; more than 

 this, as the andalusite in question occurs in a granitedike rock, 

 he suggests that itself is a product of the alteration of orthoclase. 

 In like manner the mica, which in some esses coats tourmaline, 

 and in others fills hollow prisms of this mineral, is supposed to 

 result from a subsequent alteration of crystallised tourmaline. 

 So in the case of shells of leucite filled with feldspar, or of garnet 

 enclosing epidote or chlorite or quartz, a similar transformation 

 of the interior is supposed to have been mysteriously effected, 

 while the external portion of the crystal remains intact. Again 

 the aggregates of tinstone, quartz and orthoclase having the 

 form of the latter, are, by Bisi.hof and his school, looked upon 

 a5 results of a partial alteration of previously formed orthoclase 

 crystals. It needed only to extend this view to the crystals of 

 calcite enclosing sand-grains, and regard these as the result of a 

 partial alteration of the carbonate of lime. There is absolutely 

 no proof that these hard crystalline substances can undergo the 

 changes supposed, or can be absorbed and modified like the 

 tissues of a living organism. It may, moreover, be confidently 

 affirmed that the obvious facts of envelopment are adequate to 

 explain all the cases of association upon which this hypothesis of 

 pseudomorphism by alteration has been based. Why the change 

 should extend to some pa-ts of a crystal and not to others, why 

 in some cases the exterior of the crystal is alteied, while in others 

 the centre alone is removed and replaced by a different material, 

 are questions which the advocates of this fanciful hypothesis have 

 not explained. As taught by Blum and Bischof, however, these 

 views of the alteration of mineral species have not only been 

 generally accepted, but have formed the basis of the generally 

 received theory of rock-metamorphism. 



Protests against the views of this school have, however, not 

 been wanting. Scheerer, in 1S46, in his researches in Polymeric 

 Isomorphism.t attempted to show that iolite and aspasiolite, a 

 hydrous species which had been looked upon as resulting from 

 its alteration, were isomorphous species crystallising together, 

 and, in like manner, that the association of olivine and serpentine 

 in the same crystal, at Snarum in Norway, was a case of enve- 

 lopment of two isomorphous species. In both of these instances 

 he maintained the existence of isomorphous relations between 

 silicates in which 3 HO replaced Mgi). He hence rejected the 

 view of Gustav Rose that these serpentine crystals were results of 

 the .alteration of olivine, and supported his own by reasons drawn 

 from the conditions in which the crystals occur. In 1853 I look 

 up this question, and endeavoured to show that these cases of 

 isomorphism desciibed by Scheerer entered into a more general 

 law of isomorphism pointed out by me among homologous com- 

 pounds dilTering in their formulas by «M„0o {M = hyclrogen or a 

 inet.il). I insisted, moreover, on its bearing upon the received 

 views of the alteration of minerals, and remariied, " The gene- 

 rally admitted notions of pseudomorphism seem to have origi- 

 nated in a 100 exclusive plutomsm, and require such varied hypo- 

 theses to explain ihe different cases, that we are led to seek for 

 some more simple explanation, and to find it, in many instances, 

 in the association and crystallising together of homologous and 

 isomorphous species. "J Subsequently, in 1S60, I combated 

 the view of Bischof, adopted by Dana, that "regional meta- 

 morphism is pseudomorphism on a grand scale,'' in the following 

 terms: — 



" The ingenious speculations of Bischof and others, on the 

 possible alteration of mineral species by the action of various 

 saline and alkaline solutions, may pass for what they are worth, 

 although we are satisfied that by far the greater part of the so- 

 called cases of pseudomorphism in silicates are purely imaginary, 

 and, when real, are but local and accidental phenomena. Bischof 's 

 notion of the pseudomorphism of silicates like leldspars and py- 



• Address of Prof. T. Sterry Hunt on retiring from the office of President 

 of the American Association for the Advancement of Science ; abridged 

 from the " American Naturalist." 



t Pog£. Annal., Iw-iiu 319. 



t Ibid. 



