Prof. How on the Mineralogy of Nova Scotia. 33 



of the anhydrite in which they are imbedded; these surfaces 

 are dull. The nodules are generally about the size of filberts or 

 pigeons' eggs, but occasionally larger ; the largest specimen I 

 have is a fragment about 2 inches in diameter : they sometimes 

 show, when detached, a subvitreous lustre on the exterior. The 

 mineral is translucent in thin fragments ; under the microscope 

 its powder is seen to be perfectly transparent and crystalline; 

 the form, to judge from the cleavage, is possibly rhombic. The 

 greatest hardness is about 3*5 ; specific gravity 2*55. Before 

 the blowpipe, the hardest fragments decrepitate strongly, and all 

 fuse readily to a clear colourless bead, making the inner flame 

 green, deep green when the mineral has lain some time in water. 

 Fragments fuse even in the flame of a lamp to a colourless 

 blebby glass, which, when further heated before the blowpipe, 

 froths considerably, and finally becomes quite clear. The trans- 

 parent bead can be rendered opake by sudden insertion in, and 

 removal from, the oxidizing flame, probably from the formation 

 of bubbles of boracic acid which cannot escape till the mass gets 

 farther heated ; for on re-fusion the bead becomes clear again, 

 and remains so on prolonged heating. These reactions distin- 

 guish the mineral from natroborocalcite, which colours the flame 

 yellow at first, and fuses readily to a clear colourless bead, which 

 can also be rendered opake by the method just given, but which 

 on prolonged fusion becomes so reduced in bulk as to leave the 

 wire-loop nearly empty ; the flame meanwhile becomes decidedly 

 greenish yellow. In the former case the presence of silica is no 

 doubt the cause of the permanent transparency. A minute 

 quantity of either mineral with a drop of dilute hydrochloric 

 acid gives the boracic-acid test with turmeric paper most readily. 

 The new mineral before ignition gelatinizes perfectly in two or 

 three minutes when its powder is stirred with cold hydrochloric 

 acid, — after ignition also, when left in contact merely for some 

 time. In a closed tube it decrepitates and gives much water. 

 In the following analyses the results under I. were from a nodule 

 in anhydrite; those under II. from several fragments, some of 

 which were perfectly dull and opake, while others were lustrous 

 in parts of the exterior. The absence of soda was proved by 

 testing after removal of boracic and silicic acids by heating with 

 fluor and sulphuric acid ; the boracic acid was estimated by 

 deficiency after gravimetrical determination of the other consti- 

 tuents in the regular way. Analysis of the air-dried hard mineral 

 gave : — 



Phil. Mag. S. 4. Vol. 35. No. 234. Jan. 1868. D 



