418 Miscellanies. 



Forms easily a limpid glass with soda. The strongest acids attack it, 

 when finely powdered, with difficulty. 



4. Bloiopipe characters of the supposed Pyrrhiie of the Azores ; by 

 J. E. Teschemachek. (Best. Jour, of Nat. Hist., Vol. IV, p. 499.)— 

 The minutest transparent crystals change immediately in the redu- 

 cing flame to a deep, dull indigo blue, perfectly distinct ; the edges 

 then rounded, and, after considerable exposure, fused without intumes- 

 cence ; on the application of borax, the fusion was immediate, and a 

 small transparent light brown bead remained. The largest crystal was 

 then exposed to the outer flame ; it became opaque, of a light gray 

 color ; before the reducing flame it changed apparently to black ; but 

 the blue color is clearly seen, in a strong light on the solid angles. Of 

 this crystal, the edges alone could be rounded on long exposure. 



5. Formula of the Pink Scapolite of Bolton. — Dr. C. T. Jackson 

 (Bost. Jour. Nat. Hist., IV, 504) deduces the following formula from 

 his late analysis of that mineral, (the silica, alumina and alkalies, hav- 

 ing the ratios of 4, 2, 1, respectively.) Formula, 2AI Si-f-(Ca, Na,Li) 



Si2 ; or in chemical symbols, 2iLlSi-|-(Ca, Na, Li)^ Si^. 



6. Head of Carpinchoe. — Lieut. H. C. Flagg, U. S. N., of New Ha- 

 ven, has recently presented to the Natural History Society connected 

 with Yale College, a fine skull of the Cabybara or Carpinchoe (Hydro- 

 chcBrus cabiai) from Guiana, the largest animal of the class Rodentia : 

 also the well preserved skin of an albatross. 



7. Natural Polariscope. — In the mica quarries at Grafton, New 

 Hampshire, where this mineral is obtained in large quantities for stove 

 fronts and other economical purposes, black tourmalines are frequently 

 found compressed between the laminse of mica. In looking over a large 

 quantity of this mica, I found several specimens where the tourmalines 

 were so thin as to be transparent and of a fine clove-brown color, 

 although the crystals are ordinarily quite black. The thought at once 

 suggested itself that we were here provided by nature with the means 

 for polarization, and no time was lost in constructing of two thin tourma- 

 lines and a piece of the binaxial mica in which they are imbedded, a 

 very good instrument. It will be observed that the compression of the 

 tourmalines has taken place in a plane perfectly parallel to the vertical 

 axis of the prism, and consequently in the right direction to ensure the 

 maximum effect. It is feared that the color of the tourmalines will be 

 found too dark to allow of their general use, as they must be made very 

 thin in order to admit light enough to pass. But the fact is an interest- 

 ing one, that nature should have anticipated the construction of one of 

 the most refined of modern optical instruments. B. S. Jr. 



