33 



white lead, and it is said to be used also for the adulteration of 

 fancy soaps, and also for glazing or satining wall-papei*. 



By chemical analysis, I find this rock is composed of, in 100 

 grains — 



99.25 

 It is therefore Agalraatolite. 



Remarks upon the Deep River Coal Formation were also 

 made by Prof W. B. Rogers. 



Dr. Hayes asked what chemical evidence Dr. Jackson had 

 that the North Carolina or Deep River coal is a gas coal. 



Dr. Jackson replied, that his experiments were made in the 

 usual manner, in covered platinum crucibles, (which represent 

 very perfectly the gas retorts,) and that he found the North 

 Carolina coal to produce Si-^^ per cent, of coal gas, which 

 burned with a brilliant yellow and highly illuminating flame, 

 without smoke, and did not give any sulphurous acid, or other 

 disagreeable products, while the coke resulting from torrefaction 

 of the coal was found to be of superior quality, giving less than 

 two per cent, of ashes when burned. Practical trials, made with 

 this coal at the Brooklyn, N. Y., Gas Works, had fully proved 

 its excellence as a gas coal. 



To this Dr. Hayes added, that an experiment thus made hardly 

 demonstrated, in his opinion, that the coal was a gas coal. The 

 amount of volatile matter given off from any coal, varies with 

 the rapidity or slowness of heating it, and may be made up of 

 vapor of water formed from the constituents of the coal, and 

 heavy vapors producing coal tar, together burning with a bright 

 flame, from a coal wholly unfit for making gas. The coals of 

 our Western States, and those of Scotland, offer fine illustrations 

 of the error which might be committed in an experiment of this 

 kind ; some affording a large volume of rich gas under a small 



PROCEEDINGS B. S, N. H. VOL. VI. 3 DECEMBER, 1856. 



