1826.} Anthracite, Pbtmhago, S;d. 105 



about half an ilich in diameter, and one-fourth of an inch in 

 thickness. The light in the greater number of instances was so 

 intense that I found it necessary to use double green glasses. 



The mode pursued in the analysis of anthracite and plumbago 

 was as follows. The presence of water was ascertained by heat- 

 ing a few small pieces of the substance in a glass tube, closed at 

 one end ; and the quantity of water by heating a given portion 

 in a covered platina crucible. Another portion was pulverized 

 in an agate mortar ; then a given weight of it was put into a 

 platina crucible, and kept without its cover at a red heat in a 

 small French furnace, until the whole of the carbon was con- 

 sumed ; the residue was then boiled in water for an alkali ; 

 after which operation it was heated with caustic potash in a 

 silver crucible : when the fusion of the mass was' completed, 

 water was added, and the whole then dissolved with nitro- 

 muriatic acid. By evaporating the liquor to dryness, and adding 

 acidulated water and hltering, the silex was obtained. To the 

 liquor from this operation, ammonia in excess was added, and 

 by this agent, the iron, manganese, and alumine contained in the 

 liquor, were precipitated ; the latter was separated from the two 

 former by caustic potash. No attempt was made to ascertain 

 the relative proportions of iron and manganese; this knowledge 

 not being considered important. The presence of manganese 

 was evidenced by the green colour of the alkaline fusion; and a 

 rose colour when acid was added to the liquor. No allowance 

 was made for the difference in the degree of oxidation of the 

 iron and manganese in the substances used, and the products 

 obtained, as the amount was less than one per cent, where most 

 abundant. 



The first experiments made with the globules were with 

 potash, and with carbonate of soda on silver, and on platina 

 foil ; with these agents I could not produce much effect, but by 

 using a small quantity of carbonate of lime, carbonate of soda 

 and borax, on platina foil ; their fusion, whether they were 

 coloured or colourless, opaque or transparent, was effected in a 

 few minutes. 



Eiper. 1. — A piece of the purest anthracite of Lehigh, sub- 

 jected to the blowpipe, presented numerous small white glo- 

 bules; few were tinged with violet, and two or three were 

 blackish ; the globules did not readily unite with one another; 

 however, by long continued heat, some of the globules were 

 obtained of the size of the head of a small pin ; the greater num- 

 ber of them were but feebly translucent, and could be broken by 

 a moderate force ; others, though few in number, were transpa- 

 rent, hard, and not so brittle. The white globules were not 

 magnetic, except when dark spots were present ; the blackish 

 ones were magnetic, and like the whole of them could be frac- 

 tured by pressure. The surface of the mass whitened, as 



