270 Scientific Intelligence. 



Smith. 12mo, pp. 92. Philadelphia, L897. (P. Blakiston, Son 

 & Co.) 



The extensive introduction of electrical methods into chemical 

 processes has given rise to the necessity of making electrochemi- 

 cal principles a part of higher education. In these little books 

 Dr. Oettel has given in a complete form an outline of these prin- 

 ciples and has thus done a service in this direction. The first 

 volume is devoted rather to practical chemical electro-technics 

 and the second to research methods. Dr. Smith's translation is 

 an excellent one, as was to be expected from his well known 

 position as an authority in this branch of chemical science. The 

 books will do a good service in instruction. g. f. b. 



4. Remarks on Colloidal Glass; by C. Barus. (Communi- 

 cated.) — Following the suggestions in my earlier experiments, 

 given in this Journal (3), vol. xli, p. 110, 1891, I have since been 

 enabled to impregnate glass with water to such an extent as to 

 make it fusible below 200° C. The solution occurs with contrac- 

 tion of bulk relatively to the ingredients and increasing com- 

 pressibility, substantially as already stated, (1. c.) Heated in a 

 gas burner in air, the new clear glass melts, swells up enormously 

 with loss of water to a white porous pumice resembling pith. 

 Long boiling in water turns it white superficially. 



I am now able to announce the following results: Glass as a 

 colloid is miscible in all proportions with water. 



If these solutions are sufficiently concentrated, they coagulate 

 at ordinary temperature and the congealed aqueous glass is not 

 different in general appearance from common glass. The melting 

 point of the coagulated aqueous silicate frequently lies below 200° 

 C, probably above 150° C., depending on the glass. 



Brown University, Providence, R. I. 



II. Geology and Mineralogy. 



1. Late Formations and Great Changes of Level in Jamaica / 

 by J. W. Spencer. Abstract prepared by the author of a paper 

 in the Transactions of the Canadian Institute, vol. v, pp. 324-357, 

 1898. — This paper is descriptive of the physical features ot 

 Jamaica which bear upon the evidence of great changes of level 

 in late geological times, and extends the conclusions set forth in 

 the author's work upon the " Reconstruction of the Antillean 

 Continent."* 



Speaking in a broad way, Jamaica is a dissected tableland, sur- 

 mounting another but submarine plateau, extending from Haiti 

 to the Yucatan banks, now submerged to depths of 3,000-4,000 

 feet. These banks have the lorm of old base-planes of erosion, 

 but they are traversed by deep valleys more than 2,000 feet below 

 the summit of the platform. Even within the limit of the sub- 

 marine plateau mass, the channels reach to a depth of 9,600 feet, 

 or more than 5,000 feet below the surface of the drowned plains. 



-Bull. Geol. Sci. Am., vol. vii, pp. 103-140, 1394. 



