276 Prof. How on the Mineralogy of Nova Scotia. 



this region have been used for the greater number of known 

 analyses. I have seen no mention of the mode of occurrence 

 in Western Africa ; but salt is given as an ingredient there. 

 Nevada affords it in a salt-marsh — in layers alternating with salt, 

 and in balls in the salt. In Nova Scotia we have it associated 

 occasionally with Glauber salt, calcite or Arragonite, and sele- 

 nite, but most frequently imbedded in gypsum in what have 

 hitherto been known as its only form, viz. nodules or rounded 

 balls of closely packed fibres, which are capillary or acicular 

 crystals. In the analysis made of the specimens first noticed 

 here I found very little impurity, consisting of a small quantity 

 of sulphate of sodium and of magnesium and a trace of chlo- 

 rine, which was readily removed by cold water, so that a pure 

 material was without difficulty obtained for examination ; and I 

 was led to propose the formula which Dr. Kraut subsequently pre- 

 ferred as expressing most satisfactorily, in view of all the pub- 

 lished analyses, the composition of the mineral, and which, as 

 shown in a former part of these Contributions*, does not appear 

 to me to be set aside by his later results and those of Dr. Lunge, 

 — an opinion evidently shared with Dana, who has not, in the last 

 edition of his ' Mineralogy ' (loc. cit.), accepted the conclusions 

 of the last-named chemist. It was with reference to the vary- 

 ing formulas given from time to time that Mr. Walker, a late 

 observer of the conditions under which the "so-called borate of 

 lime" is found in Peru, felt himself called upon in 1868 to se- 

 lect seven specimens representing so many distinct deposits oc- 

 curring in different basins, and to show, by analysis f, that they 

 were most dissimilar admixtures of various substances. For 

 these he (doubtless with great self-restraint) would not attempt 

 to deduce a formula ; and in this forbearance he offered an ex- 

 ample to those who, as he said, " seemed to delight in racking 

 their brains to construct a formula that will agree with their 

 particular analysis." It is obvious that the analyses given by 

 Dana are those of a definite substance, varying, however, in 

 purity, and that the Nova-Scotian specimen is the purest, with 

 one exception, of those mentioned as actually found ; so that 

 Mr. Walker's seven carefully selected muds really do not mili- 

 tate against the existence of this well-marked and interesting 

 species. 



Last year, the gypsum trade being unusually active here, not 

 less than about 106,000 tons having been shipped from Hants 

 county, and of this 81,276 tons from Windsor, in great part 

 from its own wharfs, as against 100,159 and 63,655 tons respec- 



* Phil. Mag. January 1868. 



t Chemical News, vol. xviii. p. 203. 



