Prof. How on the Mineralogy of Nova Scotia. 39 



of sodium"* in gypsum of Windsor, marked a resemblance be- 

 tween it and similar rocks containing glauber and common salt 

 in Spain &c, and, as regards boracic acid, with some in Ger- 

 many containing boracite and Stassfurthite. Now the nodules 

 of silicated borate in anhydrite and in gypsum of Brookville, 

 both rocks containing a little silica, and in gypsum of Newport, 

 bring these into the same class, so far as silica is concerned, with 

 some gypsums (originally belonging to secondary strata) in the 

 Hartz, which, according to Fropolli, contain nodules of silicate 

 of magnesia, and with those of Montmartre near Paris, which 

 hold soluble silica, or flints and chert f. Further analogy be- 

 tween these and other sulphate-of- calcium deposits is shown in 

 the fact, which I have lately learned, that nearly every specimen 

 of gypsum and anhydrite here yielding borates contains carbo- 

 nates in notable but as yet unascertained amount, consisting to 

 some extent of magnesia (of which traces appear in the borates as 

 seen in my analyses), as well as in the detection now announced 

 of Arragonite in cavities in gypsum, and of crusts of this mineral 

 or calcite on the surfaces of gypsum and anhydrite, and also 

 sometimes on the natroborocalcite and silicoborate in the former, 

 and close to and underlying the silicoborocalcite of the latter. 



These mineral contents and the numerous brine-springs of the 

 gypsiferous districts here point to sea-water as the parent of the 

 gypsum; but, as I observed in a former paper (1861) referred 

 to above, ordinary sea-water would not furnish boracic acid. 

 This acid, however, I afterwards found in a brine-spring issuing 

 in a gypsiferous district here J, and it has been met with in the 

 waters of Aachen and Wiesbaden, and, by Hunt in all the alka- 

 line waters of Canada (Ontario and Quebec) examined for it, and 

 in certain neutral waters of the same country §. These last 

 waters arise from Lower Silurian rocks ; and all those named as 

 containing boracic acid may resemble Palaeozoic sea-water rather 

 than our own. An origin for the boracic acid in the borates 

 has also been sought by myself || in volcanic waters containing 

 sulphuric acid, such as Dr. Dawson considers to have produced 

 the gypsums here by action on the deposits of carbonate of 

 lime ; but when we have it combined with silica and we consider 

 the other contents of the rocks in question, sea-water certainly 

 seems rather to be indicated. However we may derive gypsum 

 directly by either of these methods, or by others *[[, it is said 



* Loc. cit. 1857-61. 



f Hunt, Silliman's Journal, November 1859, pp. 366, 367. 

 X Trans. Nova Scotia Institute, 1865. 

 § Geology of Canada, p. 560. 

 || Loc. cit. 1857. 



51" See Hunt's elaborate paper " On the Formation of Gypsum, &c." 

 Silliman's Journal, September and November 1859. 



