14t> iJr. Brown on the JVt^re, ^c. 



The western part of the island presents moderate eleva- 

 tions ; the soil, a good medium of sand and clay, is in general 

 fertile ; but a tract near the termination is sandy and barren. 

 Some creeks penetrate to near the centre of the island, and 

 are bordered by extensive salt meadows. Except at the pri- 

 mitive range, I haye observed in no part of the island large 

 beds of rock that can be called in place ; but rolled masses of 

 greenstone, sandstone, gneiss, granite, red jasper, and indu- 

 rated clay, appear in general sparingly, but sometimes in 

 abundance, on the surface. Lignite has been found in smaiT 

 quantities in the western part of the island. A chalybeate 

 spring, of no great strength, is the only mineral water met 

 with in Richmond county. The ponds, wells, and streams, 

 contain a soft water, holding no lime in solution. 



We have already published (p. 64.) Mr. Pierce's dis- 

 covery of the pulverulent carbonate of magnesia, and have 

 pointed out its connexion with Dr. Bruce's previous dis- 

 covery of the hydrate of magnesia, or pure magnesia com- 

 bined with water only. Mr. Pierce has now added another 

 important link to this chain'^ and future mineralogists may 

 quote the vicinity of New- York as affording, 



1. Pure magnesia, crystalhzed and combined with water onl3^ 



2. Carbonate of magnesia, pulverulent and white. 



3. Carbonate of magnesia, in very delicate and perfectly 



white acicular crystals. 

 We possess specimens of them all. 



Art. X. On a curious substance which accompanies the 

 native Nitre of Kentucky and of Jlfrica. Communicated 

 in a letter to the Editor^ from Samuel Brown, M.D. 

 late of Kentucky, now of the Alabama Territory. 



REMARKS. 



J. HE scientific public were several years ago laid under 

 obligations to Dr. Brown, for a very interesting and instruc- 



