Dr. Meade's notice of the Tioga Coal. 33 



posited, as is generally the case, in a series of beds of sand- 

 stone, accompanied by shale or argillaceous slate, abound- 

 ing with vegetable impressions and resting on secondary 

 limestone, containing fossil remains. It is also an important 

 circumstance, that in the neighborhood of the coal mine is 

 found abundance of iron ore ; specimens of which I have 

 examined, and find it to be of that species which is called 

 iron stone or argillaceous iron ore, precisely of the same 

 character as that which accompanies the beds of coal in 

 England, and which is worked so extensively in that country. 



The external appearance of the Tioga coal, differs so little 

 from the well known character of the best Liverpool or New- 

 castle coal, that it scarce requires a description. Its color is 

 velvet black with a slight resinous lustre, its structure is slaty 

 or foliated, and its layers, as in the best English coal, divided 

 into prismatic solids with bases slightly rhomboidal ; it is 

 easily frangible and slightly soils the fingers. The specific 

 gravity is 1.287. It burns with a bright flame and conside- 

 rable smoke, with a slight bituminous smell ; a sort of ebulli- 

 tion taking place, and as the heat increases an appearance 

 of semifusion leaving a light residue or scoria. 



These characters are quite sufficient to place it in the rank 

 of the best bituminous coal, but as it may be satisfactory to 

 establish by experiment the quantity of carbon which it con- 

 tains, upon which its most essential value depends, I sub- 

 mitted it to the following experiments. 



It has been long since established that nitre detonates with 

 no oily or bituminous substance until such matter is first redu- 

 ced to coal, and then only in proportion to the quantity of 

 carbon it contains ; it has also been ascertained, that when 

 the detonation ceases, it requires about fifty grains of carbon 

 to saturate the oxygen in the nitric acid of five hundred grains 

 of nitrate of potash ; taking this rule therefore for a guide, I 

 fused five hundred grains of nitre in a large crucible, and 

 having reduced one hundred grains of coal into a coarse 

 powder, I gradually projected it, in small portions at a time, 

 into the crucible on the ignited nitre, as long as any detona- 

 tion took place ; observing the necessary caution that the 

 coal was not too finely powdered, and next that it was slowly 

 poured in, otherwise a part of it may have been projected 

 out of the crucible by the deflagration of the nitre. Having 

 made this experiment several times, I found that it required 

 seventy-five grains of the coal to decompose the five hundred 



Vol. XIII.— No. 1. 5 



