OF ARTS AND SCIENCES. 159 



are given for comparison the results of an analysis of a mica from 

 Hirschburg, taken from Dana's System of Miuei-alogy, last edition, 

 and classed by him among the muscovites. 



100.60 100.87 



Oxygen Ratios. — Bases with water to silica are as 4 : 5 nearly. 

 Bases without water to silica are as 2 : 3 approximately. 



RO + H,0 : RA : SiO^ = 5 : 11 : 20. 

 RO:EP3:SiO2=2:ll:20. 



Conclusions. — Here, then, we have an evident product of altera- 

 tion, with some of the characters of a vermiculite, which differs in 

 composition from ordinary muscovite mica only in the absence of 

 fluorine, and the presence of a somewhat larger amount of magnesia. 

 Possibly muscovite may pass into vermiculite, and this mica from 

 Texas may represent the first step in the alteration ; but if so, inter- 

 mediate stages must be found, and then this work may help to answer 

 the question. As will be seen, the composition of the Texas mica 

 agrees closely with that of the mica from Hirschburg, the difference 

 in the relative amounts of AlPg and FcgOg being unessential. 



II. — ANALYSIS OF A CRYSTALLINE SCALE FORMED 

 IN THE MANUFACTURE OF SODIC BICARBONATE 

 BY THE AMMONIA PROCESS, AT SYRACUSE, N. Y. 



By George W. Leighton, B. S. 1886. 



The material here described was deposited on the inner surface of an 

 iron tank in which vapors consisting of NHg, COg, with small quantities 

 of H2S, are passed through brine holding in solution NaCl, MgClj. 



