Miscellanies. 183 



I hope, ere long, to furnish a more particular account of the varie- 

 ties mentioned in this communication. Ebenezer Emmons. 

 Williams College, Aug. 15, 1834. 



JVote, by C. U. Shepard. — A second communication from Dr. 

 Emmons, relating to the foregoing, has been received, from which it 

 appears, that he has ascertained the specific gravity of the mineral 

 to be 3*5. He adds, that "the point with me is to prove that it con- 

 tains carbonate of strontia, or consists of it in the main : I do suppose 

 that it contains some sulphate of baryta or sulphate of strontia." 



Dr. Emmons was kind enough to enclose a few fragments of the 

 mineral in the letter, which, in hardness and structure, agreed with 

 the description he has given. As the fragments appeared remarka- 

 bly pure, I thought it worth while to settle the question of their con- 

 taining either of the sulphates of baryta, strontia, or lime. 



Accordingly, 1 heated 8 grs. of the mineral, in the state of an im- 

 palpable powder, to a dull redness, in a plaiina crucible ; and on re- 

 storing the crucible to the balances, found that it had lost 0.2 grs. or 

 2.5 per cent. The 7.8 grs. were introduced, with extreme caution, 

 into a small glass flask, and dilute hydrochloric acid affused at inter- 

 vals, until the effervescence had nearly subsided. Heat was then 

 applied, for a few minutes; when nearly the whole of the powder had 

 disappeared. The quantity remaining undissolved appeared too mi- 

 nute to allow of being withdrawn from the flask and estimated by the 

 scales. I attempted to form an opinion of its quantity, therefore, by 

 withdrawing the supernatant solution. This was done with care, and 

 the washings of the flask added to the fluid. The solution was evapo- 

 rated, in the platina crucible, to dryness, and maintained for five min- 

 utes at a red heat. The chloride of strontium thus obtained weighed 

 8.7 grs., which is equivalent to 4.35 of strontium. But the strontium 

 in 7.8 carbonate of strontia = 4.637. The difference of 0.28 (be- 

 tween 4.35 and 4.637) is to be attributed to the undissolved matter 

 in the flask, and to loss. The appearance of the undissolved portion 

 being that of minute grains, it occurred to me that it might still be 

 carbonate of strontia; and that the reason of its not having been dis- 

 solved was a want of pulverization. Accordingly, I treated it with 

 an additional portion of hydrochloric acid and heat, when it soon 

 yielded a perfect solution. 



I therefore fully coincide with Dr. E. in the opinion that this min- 

 eral is the Strontianite. 



Yale College, August 26, 1834. 



