January 6, 1899.] 



SCIENCE. 



33 



parisoa was made between these methods and 

 others that have been proposed. Attention was 

 called to the necessity of defining the sub- 

 stances present by the methods by which they 

 are to be determined and reckoned, as it not in- 

 frequently happens that there are differences of 

 opinion as to the form in which they occur and 

 the methods for determining them, and a dis- 

 pute is most easily avoided by a prior technical 

 convention. Thus there is a difference of opin- 

 ion as to the form in which a portion of the 

 nitrogen present in these acids occurs, some re- 

 garding it as in the form of hyponitrous acid, 

 others as nitrosulphuric acid, but without ex- 

 pressing any opinion on this point the specifica- 

 tions simply required that it should be deter- 

 mined in a carefully prescribed manner and 

 reckoned as N.O^, and that as thus determined 

 and reckoned it should uot exceed a certain 

 percentage of the mixture. The data of a con- 

 siderable number of analyses showing the per- 

 centage composition and specific gravities of 

 both original acids and spent acids from the gun- 

 cotton manufacture was given, and the differ- 

 ences between the amounts of sulphuric acid in 

 the different operations was seen to be remark- 

 ably constant, showing the mixture to be well 

 proportioned for this purpose. Observations 

 were made on the permanency of composition 

 of the mixed acids stored in darkness and in 

 sunlight ; on the color of the acids as a criterion 

 of the amount of nitrogen oxides present ; on 

 the change of color produced by heating them ; 

 on the freezing of the acids and the rate of ex- 

 pansion of different mixtures. The specific- 

 gravity bottle used, which was devised by Pro- 

 fessor Barker, and which was particularly 

 adapted to this work, was exhibited. 



William H. Krug, 



Secretary. 



HARVARD UNIVERSITY : STUDENTS' GEOLOGICAL 

 CLUB, DECEMBER 6, 189S. 



Mr. p. S. Smith described ' An Occurrence of 

 Corundum in Kyanite.' This paper will be 

 published soon in full. Mr. J. M. Boutwell 

 spoke on 'Tides : Their Character and Cause.' 

 After reviewing our incomplete knowledge of 

 tides in the open ocean, he explained a method 

 of expressing, with plotted curves, certain facts 



obtained from observations on tides, as they 

 traverse continental shelves and estuaries. 

 These curves show a perfect homology between 

 wind waves and true tidal waves in form, range, • 

 length (better termed breadth) and velocity. 

 Under the cause of tides, the main points of the 

 explanation advocated by Hagen, Airy, Dar- 

 win and others were presented. 



Geological Conference, December 13, 1S9S. — In 

 a communication entitled 'Dikes and Veins,' 

 Professor Shaler considered the origin of fissures 

 occupied by these bodies. Field observation 

 near the Spokane Placer, Montana, shows that 

 intrusives part rocks along bedding planes more 

 readily than transverse to them. Professor 

 Shaler suggests that water, mechanically in- 

 cluded in beds at the time of their deposition, 

 becomes heated by an approaching, intrusive 

 mass ; and that by expanding it opens the way 

 for the intrusion along previously existing, 

 structural planes. According to this theory, in 

 a region where the intrusives are of different 

 age, the earliest intrusive should show evidence 

 of its easy entrance along fissures opened by 

 expanded water ; and subsequent intrusives 

 should exhibit signs of more difficult entrance, 

 owing to the exhaustion of assisting waters. 



Mr. Robert DeC. Ward presented ' Some Ob- 

 servations on the Medanos of Peru,' which will 

 be published in a future issue of this Journal. 

 J. M. Boutwell, 

 Recording Secretary. 



TOREEY BOTANICAL CLUB, NOVEMBER 30, 1898. 



On discussion of enlargement of the program 

 for excursions, it was arranged that field meet- 

 ings be provided on Saturdays after the first of 

 January, for the purpose of studies of crypto- 

 gams and of winter stages of higher plants. 



The first paper was by Mr. Marshall A. 

 Howe, ' Remarks on some Undescribed Califor- 

 nian Hepaticse,' and consisted of the description 

 of three new species, soon to be published. 

 Beautiful plates illustrating these species were 

 exhibited, the work of Mr. Howe, to form part 

 of the forthcoming volume of the Memoirs of 

 the Torrey Club. 



The second paper was by Professor Francis. 

 E. Lloyd, on ' The Nucleus in Certain^ Myxo- 



