350 1>R0CEEDINGS OP THE ACADEMY OF [1886. 



across for examination, projected the seed into his face while the 

 capsule was being examined with a lens, indicating a projecting 

 power not before known to exist in the species. 



November 23. 

 Mr. John H. Redfield in the chair. 

 Nineteen persons present. 



Manganese Zinc Serpentine from Franklin, N. J. Prof. 

 George A. Koenig placed on record the determination of a man- 

 ganese zinc serpentine from Franklin, N. J. The material was 

 collected in summer, 1885, as a very peculiar Willemite, so called 

 at the mine. It is a very compact mineral substance, having a 

 dark brown dull color and subconchoidal fracture, the splinters 

 resembling horn chips. It is translucent on the edges, and when 

 ground into a thin plate transmits a uniform brown-j'ellow light. 

 Under the microscope this section of the purest material shows 

 strings of minute black grains. Between two crossed nicol 

 prisms the section appears light, proving a crystalline structure 

 other than isometric. But a few grains, a light yellow in ordi- 

 nary light, behave like an isometric substance, and are probably 

 grains of yellow garnet, which is one of the associate minerals. 

 Spec. gr. := 2*635. It is decomposed by sulphuric acid like 

 Serpentine. 



The mean of two well-agreeing analyses gave 



Si02 = 42-20 (including 0-298 MgO,0-2 ZnO). 



Fe203= 2-80 



MnO = 7-44 



ZnO = 3-90 



MgO = 29-24 



H2O = 14-04 



99-62 

 Let Fe^O^ be supposed to be present as Franklinite, requiring 

 0*8 ZnO and 0-53 ZnO, then we have 4-15 per cent, of Franklinite 

 mixed with the silicate, and the composition is now 



1-390 

 1-462) 

 0-194 > 1-733 

 0-077) 

 1-533 



100-16 

 This gives the ratio, SiO^ : RO : H^O 



1 1-25 1-1 



