occurring in the Gypsum of Nova Scotia. 115 
of course, become anhydrous on exposure to dry air); the results 
then become :— 
Oxygen. Ratio. Calculation. 
a a Re OE FR SEE eta t BLS TE Tre 
Lime, : - 15°5=> £44 3°08 3 Cad 84 15°46 
Soda, ; orb =i' 144 1 NaO 31 Dy’ é 
Water, . Borge 17'o2. | Lae: 12H) 408 20°11 
Boracic acid, . 59:10=40°47 2310 9BO, 3141 . 58°48 
99°98 5371 100°00 
—corresponding to the formula, 
NaO, 3 CaO, 9 BO,+12 HO. 
I am very well aware that it is unsafe to base a formula upon a 
single analysis, especially of a mineral substance, and most espe- 
cially after making deductions as above, and I cannot, in this case, 
insist on the one brought out, but it is not anomalous. We find 
rather complex combinations both in the natural and artificially 
formed compounds of boracic acid; thus, 
Hydroboracite,* = 3 CaO, 4 BO, +3 MgO, 4 BO,+18 HO, and 
Larderellite,* =NH,O, 4 BO,+4 HO; 
while Laurent describes} a salt=5 NaO, 24 BO,+52 HO, and 
Rose onef = 3 CaO, 5 BO, when ignited; and it is a little curious 
that the formula given above includes the soda compound corre- 
sponding to Larderellite and the salt of Rose— 
NaO, 4 BO,+3 CaO, 4 BO,+12 aq. 
I mentioned that the mineral presented no appearance of crystalline 
structure to the naked eye. Not having at hand, at the time I was 
at work upon it, a sufficiently good microscope, I sent a portion of 
the mineral to Professor Robb, of the University of New Brunswick, 
at Fredericton, with a letter stating my results and my doubt as to 
the substance being crystalline. I received this answer—“ In spite 
_ of your odd formula, the mineral just as I got it, untouched and 
unwashed, is perfectly crystalline in every particle. A good power 
is required; but with a magnifying power of about 350 diameters 
there is no difficulty, the form comes out as sharp as possible. The 
crystals are excessively thin translucent tables or plates. They 
have a rhombic outline, and the angles probably = 80° or more, 
* Dana’s Min., 4th ed., 394, 395. 
t Liebig und Kopp’s Jahresbericht, 1849, p. 226. 
t Ibid., 1842, p. 313. 
