ELISHA MITCHELL SCIENTIFIC SOCIETY. 6l 



is calcium sulphate, and we might expect to find it composing the 

 No. 1 deposit. Through the kindness of Mr. Donald McRae, of 

 "Wilmington, N. C, I have secured a piece of this No. 1 deposit. It 

 is very hard and tough, of a light greyish color, and dense structure. 

 The analysis shows : 



Loss at lOO^C. 



9 



Loss at iij°C I 



Insoluble in HCl (after fusion) i 



Ferric oxide 



Magnesium oxide ... 



Calcium oxide 34 



Sulphuric anhydride 49 



Undetermined . . 2 



Per cent. 



74 

 96 



GO 

 32 

 89 



79 

 19 

 II 



The SO3 calculated to CaO.SOg gives 83.62 per cent., contain ng 

 CaO 34.43 per cent., which leaves .36 per cen . CaO, in some other 

 combination. It is not likely that any of the SO3 is combined with 

 the magnesium, as none was yielded to boiling water. It may be 

 that the excess of CaO, and the MgO exist in some form not deter- 

 mined. But that the deposit is calcium sulphate we cannot doubt, 

 nor that it was formed as we would expect it to be, viz : in the first 

 evaporating pan. 



This specimen was from the old salt works at Masonboro Sound, 

 New Hanover county. 



