852 



SCIENCE. 



[N. S Vol. V. No. 126. 



vania and West Virginia entirely from the west- 

 ern sea ; in these deposits no marine fossils are 

 found, but only land plants and fresh- water 

 Crustaceans and a few fresh-water mollusks. ' ' 



A table showing the correlation of the Coal 

 Measures of Arkansas and similar deposits in 

 Indian Territory, Texas, the Mississippi Valley, 

 Pennsylvania, China and other parts of Asia, 

 Russia and the Ural Mountains, India and 

 South America, closes what may be termed the 

 first part of this contribution. The remainder, 

 pages 25-72, consists of an annotated list of the 

 Marine Fossils of the Arkansas Coal Measures, 

 together with a check list showing their strati- 

 graphic distribution and the localities of their 

 occurrence in Arkansas and elsewhere. Nine 

 excellent plates accompany the text. A new 

 species of Gastrioceras, G. branneri, and a variety 

 of Pronorites cyclobolus, Phillips, called arkansi- 

 ensis, are described. A description of the trilo- 

 bite Phillipsia (griffithides) ornatea, by Capt. A. 

 W. Vogdes, U. S. A. , quoted from the Proceed- 

 ings of the California Academy of Science,* is 

 also inserted. 



By those interested in the organic side of 

 geology Professor Smith's paper will be read 

 with much satisfaction. The comparative study 

 of faunas, their relations and distribution, is a 

 line of investigation which promises much in 

 the near future. 



Febdeeic W. Simonds. 

 University of Texas. 



Clay Deposits of Missouri. By H. A. Whbelek. 



Missouri Geological Survey, Vol. XI., 622 pp., 



39 pi. Jeflerson City, 1896. 



The recent report upon the Missouri clays, 

 while essentially economic in character, dis- 

 cusses a number of problems of wide scientific 

 interest. Among these the nature of plasticity 

 as exemplified in clays is perhaps the most im- 

 portant. Professor Wheeler finds, as a result of 

 physical tests and the microscopic examinations 

 of Haworth, that the fine plate theory of John- 

 son and Blake f is the only one which satisfac- 

 torily explains the facts, and that fineness in 

 itself has no real bearing on the plasticity. 



It is found that the fusibility of a clay is a 



* Second Series, Vol. IV., p. 589 et seq. 

 fAm. Jour. Sci. (2), XLIII., p. 357. 1867. 



function not only of the chemical composition, 

 but of the fineness of grain and the density. 

 The following formula is developed and thought 

 to be satisfactory for approximate results, but it 

 is held that absolute results can only be ob- 

 tained by testing. 



N 



FF= 



X>+D'+C 



In this F F represents the numerical value of 

 refractoriness. N represents the sum of the 

 non-detrimental constituents, or the total sil- 

 ica, alumina, titanic acid, water, moisture 

 and carbonic acid. D represents the sum 

 of the fluxing impurities or the alkalies, 

 oxide of iron, lime and magnesia. D' repre- 

 sents the sum of the alkalies, which are es- 

 timated to have double the fluxing value of 

 the other detrimentals, and hence are added 

 twice. C has the following values : 



There are a large number of physical tests, 

 chemical analyses and detailed descriptions of 

 processes, and the work is one of wide interest 

 and considerable value. 



H. FosTEE Bain. 



SCIENTIFIC JOURNALS. 



AMEEICAN CHEMICAL JOURNAL, MAY. 



On Urethanes : By O. FoLlN. When sodium 

 methylate is treated with acetbromamide the 

 yield is not, as might be expected, a hydroxyla- 

 mine derivative, but a urethane which is formed 

 by a molecular rearrangement during the course 

 of the reaction. The purpose of the author was 

 to test this reaction, to find out if it was general 

 and also the efiect of different negative and 

 positive groups substituted in the bromamide. 

 As a result of a number of experiments with 

 different radicals, it was found that the differ- 

 ence in the nature of the radical did not affect 

 the reaction, which is a general one that can be 

 used in the preparation of urethanes. The 

 urethanes when treated with phosphorus penta- 



