in Gypsum of Nova Scotia. 1] 
and the air dry substances gave the following results on analysis ; 
the water was determined by ignition, the lime, magnesia an 
sulphuric acid in one portion of the ignited residue, and the soda 
in another, after its treatment with flnor-spar and sulphurie acid 
for separation of boracic acid, which was, of course, estimate 
by deficiency : 
I. II, 
Lime - ~ - - . . 4 14-21 liga 
See eee 7250 —— 
Sulphuricacid - - - - - 398 = —— 
Magnesia - - - - - 062 — 
Wt Ss es mite ro 4." Lo TSS SSONE 
Boracicacid- - - - - 63-98 sect 
100°00 
The quantity of mineral obtained did not permit me to make 
more than one analysis and retain a little as a specimen for iden- 
tification, but these results as well as the characters already men- 
tioned and the crystalline structure to which I shall presently 
advert, are, I think, sufficient to show that it is specifically 
distinct from Natro-boro-caleite (see analyses quoted). On the 
assumption that the magnesia and sulphuric acid are accidental, 
and that the latter is combined with the former and with a quan- 
tity of soda equivalent to that of the acid not required by the 
magnesia, I have calculated the preceding results (1) after making 
these deductions, and at the same time taking away the amount 
of water necessary to render the MgOSO,=MgOSO,+7 aq. ; 
(the hydrated sulphate of soda would of course become anhydrous 
on exposure to dry air); the results then become : 
Calculation. 
a Oxygen. Ratio. 
Lime, 15°55 gt 3°08 3Ca0 84 15°64 
Soda, 561 = 144 1:00 NaO 81¢ 2 2ae 
Water, 19°72 =1752 12°16 12HO 83=6:108_~—S 200-11 
Boracic acid, 59°10  <==4047 2810 9B03 3141 58-48 
99°98 5871 00°00 
corresponding to the formula, 
NaO, 3Ca0, 9B0,+-12HO 
Lam 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,* = 8Ca0, 4B03-+3MgO, 4BO,+18HO, and 
Larderellite,* = NH4O, 4B03+4HO. 
* See Dana’s Min. 4th Ed. pp. 394, 395. 
