﻿272 Prof. How on the Mineralogy of Nova Scotia. 



These numbers lead to a formula including these elements, 



llCaO, SiO 2 , 9S0 3 , 3B0 3 , 20 HO, 

 as seen in the subjoined comparison : — 





Calculated. 







A 





Found. 

 18-80 



20HO 



. =180 



18-30 



HCaO 



. =308 



31-30 



31-66 



9 SO 3 



. =360 



36-58 



36-10 



SiO 2 



, . = 30-81 



3-14 



3-31 



3B0 3 



. =105-12 



10-68 



[10-13] 





983-93 



100-00 



100-00 



which brings out the fact that there is close accordance between 

 the theoretical and the experimental percentages. 



The second nodule analyzed was sent to me from Winkworth. 

 It had not so crystalline an exterior as that just described : the 

 upper part consisted of selenite, the lower of a layer of earthy 

 gypsum about an eighth of an inch in thickness ; the intervening 

 portion, forming the greater part of the whole nodule, which 

 was about the size of the foregoing and weighed nearly 500 

 grains, had characters agreeing closely with those just described. 

 The hardness was a little above 3 ; before the blowpipe the flame 

 was coloured green, and a bead clear at the edges was obtained 

 at first ; on blowing for some time, continuous bubbling, with 

 the gradual shrinking of the bead to an opaque coating on the 

 wire, took place. Scrapings had just the appearance of those of 

 No. 1 under the microscope. In the analysis a little carbonate 

 of calcium was found ; this was deducted, the amount (4*47 per 

 cent.) being calculated from the quantity of carbonic acid obtained. 

 The percentages on the air-dried mineral were these : — ^ 



No. II. 



Water - . . 18-00 



Lime 31*14 



Sulphuric acid . . . . 31*51 



Silicic acid 4'98 



Boracic acid (by difference) [14*37] 



100*00 



which lead to a formula including these terms, 



IlCaO, SiO 2 , 8S0 3 , 4B0 3 , 20HO, 



as appears on comparing the theoretical and experimental per- 

 centages, thus : — 



