Prof. How on the Mineralogy of Nova Scotia. 279 



in 1857* as affording the specimens of crystals of Glauber salt 

 with Ulexite, then for the first time made known to occur in this 

 province, has since undergone great changes from extensive work- 

 ings in various parts. Last autumn, at a^depth of 30 feet below 

 the original surface, and from 2 to 5 feet below a level which 

 had been a surface for two or three years and is now covered 

 with dirt, a road was made through solid gypsum; and on 

 both sides of this- road was observed a crust covering a consider- 

 able area of the rock. When first exposed it was transparent, and 

 it became opaque and powdery on exposure to the dry air ; there 

 were also observed here and there tufts of small prismatic crys- 

 tals. The crust consisted essentially of Glauber salt ; an ana- 

 lysis of some transparent portions, left a night only in the labo- 

 ratory, gave — 



Water . . . . : 54-10 



Sulphate of soda and a little impurity . 45*90 



100-00 

 Pure Glauber salt contains 56 per cent, of water ; the impurity 

 noticed consisted of sulphate of lime and magnesia and perhaps 

 chloride of sodium, as a trace of chlorine was found in some of 

 the crust. The tufts of needles were sulphate of magnesia. It 

 is a most interesting fact that the crust contained a minute 

 quantity of boracic acid ; several trials with turmeric paper in 

 the regular way brought out a distinct reaction, not on a single 

 dipping and drying, but on repeating this process once or more. 

 With regard to magnesia, I have found it a pretty constant in- 

 gredient in our gypsum, sometimes to a notable amount ; I have 

 also proved the existence of probably a considerable percentage 

 in limestone in contact with gypsum at one place. 



The Borates as Fluxes in Welding. — As was to be expected 

 from the fusibility of Ulexite and Howlite, they have both been 

 found most perfect substitutes for borax in welding. The joint 

 of a piece of hard cast steel welded with a specimen of Howlite 

 proved perfect when the edges were beaten with a sledge-ham- 

 mer ; and both steel and iron have been welded with Ulexite. 



Variable loss of Water by Forms of Crystallized Gypsum on 

 Heating. — In the course of researches on gypsum I have become 

 acquainted with some curious facts respecting the loss of water 

 on heating its varieties. I found that when a specimen of fibrous 

 gypsum and one of tabular selenite were heated side by side in 

 an air-bath, the latter began to lose water at 190° P. ; in about 

 thirty minutes it had lost 0*94 per cent. ; as the temperature 

 rose, during three hours, continued loss ensued, till it amounted 

 to 6*39 per cent, at 209° F., while the fibrous gypsum remained 

 * Silliraan's Journal, September 1857, p. 230. 



