Analysis of Charlestotcn Limestones. 365 



2. Greyisli-broxon Limestone, ivith splintery fracture. 



When fresh broken, like the former, it emitted a foetid odour, 

 which was of momentary continuance. It afforded, on analysis, 

 the following ingredients : — 



Carbonic Acid, 42-3 ; Lime, 51-6 ; Magnesia, 092 ; Alu- 

 mina, 1-8; Silica, 276; Iron, 0-35; Manganese, a trace; 

 Carbon and Sulphur, 0-26; Naphtha, 013; = 10012. 



3. Compact ash-grey Limestone. 



On breaking, did not emit any particular odour. Its consti- 

 tuent parts I found to be as follows : — 



Carbonic Acid, 4025 ; Lime, 47-05 ; Magnesia, 2-59 ; Alu- 

 mina, 095 ; Silica, 79 : Iron, 0-56 ; Manganese, a trace ; 

 Carbon, 07 ; Naphtha, 07 ; = 99-44. 



To ascertain whether any sulphuretted hydrogen was present 

 in the gas evolved during the solution of the limestone in mu- 

 riatic acid, a hundred grains of each of the hmestones were se- 

 parately dissolved in gas bottles. Within the bent tubes of 

 these bottles, rolls of paper, covered with white lead, were placed, 

 and the extremities of the tubes were conducted nearly to the 

 bottoms of vials, into which had been poured a little very strong 

 fuming nitrous acid. By transmission of the gas through these 

 vials, its peculiar odorant principle was completely destroyed, 

 and the nitrous acid contained in them being diluted with distil- 

 led water, after it had stood for some time, there was observed 

 in it a barely perceptible quantity of whitish matter, resembling, 

 in its appearance, sulphur deposited from hydrogen. The test 

 papers were a little darkened by the gas from the ash-grey lime- 

 stone, so very sHghtly so, that a close comparison with the ori- 

 ginal tint of the paper was necessary to discover the change ; 

 the others were a shade or two deeper in colour. 



Judging from the appearance of the matter undissolved by 

 the muriatic acid, these limestones, perhaps with the exception 

 of the last, are not strictly uniform in composition, some of the 

 constituent parts seeming to be only mechanically mixed, and 

 unequally disseminated throughout the mass. The one which 

 contains the greatest portion of naphtha, carbon, and sulphur, 

 is also that which is lowest in the stratification. 



