454 RECORD OF SCIENCE FOR 1886. 



paper of Scbedtler on tourmaline is especially exliaiistive, describing- 

 in detail the methods and results of the investigation. A series of 

 plates sliow the remarkable distribution of the electrical condition over 

 diflereut crystals as exhibited by the arrangement of the red lead and 

 sulphur powdered over them, after the method first proposed by Kundt. 

 The subject of the specific heat of minerals has been investigated by 

 Oberg and by Joly with interesting results. The latter author has 

 also attempted to determine the relative fusing points of different min- 

 erals by means of an electrical current in connection with an apparatus 

 which he calls a meldometer. He proposes some modifications in the 

 accepted scale of fusibility (von Kobell's) based upon the results of his 

 experiments. 



CHEMICAL MINERALOGY. 



A series of important papers devoted to an investigation of the chem- 

 ical composition of some American species has been issued by F. W. 

 Clarke. One of these embraces the group of minerals of Litchfield, 

 Maine, and more especially the elseolite, cancrinite, and sodalite, with an 

 alteration product of the latter called hydronephelite, described on a 

 following page. The results of the analytical work on these minerals 

 are accompanied by a discussion of their relation to each other, exem- 

 l>lified by structural formulae. In a second paper the same author takes 

 up the lithia micas, and gives the results of much careful chemical 

 work upon them. Analyses are given of the lepidolite from several 

 towns in Maine, viz, Eumford, Paris, Hebron, Auburn, and Norway. 

 They lead to the generally accepted formula Al2LiKF2Si309, and show 

 a variation in water and fluorine, probably to be explained by a replace- 

 ment of the latter by hydroxyl. The iron -lithia micas of Cape Ann, 

 Massachusetts, including thecryophyllite and lepidomelane (anuite),are 

 also investigated and shown to bear an im])ortant relation to each other. 

 Still another paper, by the same author, in this case associated with J. 

 S. Diller, is devoted to a chemical and microscopical investigation of 

 the turquoise of New Mexico. Analyses of three distinct types were 

 made: the bright blue slightlj' translucent variety, the pale blue, with 

 slight greenish cast, and the dark green opaque kind. These analy- 

 ses are compared with others of the Persian and California mineral by 

 Church and Moore, respectively, and shown to agree as well as could be 

 expected, considering the nature of the material. The composition is 

 made out, as expressed by the formula 2Al2'J3. P2O5. 5H2O, with variable 

 amounts of a copper salt, 2CuO. P2O5. 4H2O. A detailed description of 

 the microscopic appearance of the mineral and of the inclosing rock 

 follows. 



Penfield and Harper discuss at length the composition of beryl and 

 herderite. The former subject had been earlier studied by Penfield 

 (see report for 18S5), with the result of showing that beryl often con- 

 tains alkalies to an extent not before imagined, and also water of 

 constitution. The true formula of the species was, however, left in 



