THE TECHNOLOGIST. [May 1, 1864. 



466 A VISIT TO THE WORKS OF 



a few notes on plumbago, or, to use its more correct name, — graphite. 

 The old mineralogists, misled by its remarkable metallic lustre, placed 

 graphite among the metals, and at the present time there are doubtless 

 many persons who accept " black-lead " as an appropriate name for this 

 substance. In most dictionaries graphite is defined as " carburet of iron," 

 in accordance with the opinion formerly held by most chemists that it 

 was a compound of carbon and iron. This definition is now known to be 

 incorrect, for, although iron is generally present in graphite, it must not 

 be regarded as an essential constituent, any more than the silica or 

 alumina which usually accompanies it. The iron, silica, and alumina, 

 when present, are simply in a state of mixture, and not chemically com- 

 bined. Graphite is one of the forms of carbon, that Protean element 

 which also occurs native as the sparkling diamond and the black and 

 lustrous anthracite, and which also appears in the familiar shapes of 

 charcoal, coke, and lamp-black. According to Dr. Wood's analysis of a 

 sample of the graphite used at these works, it contained upwards of 98 

 per cent, of pure carbon, the remainder being silica with mere traces of 

 iron and alumina. Few samples have been found to contain less than 

 95 per cent. The variform character of carbon is exhibited by graphite 

 itself, for it is sometimes crystalline and sometimes amorphous. The 

 crystallised, or foliated graphite, is found occasionally in six-sided tabular 

 crystals, but commonly in foliated or granular masses. It is chiefly 

 obtained from Ceylon, where it is found imbedded in quartz. It is 

 also found near Moreton Bay, in Australia ; in the States of New 

 York and Massachusets, and in Siberia. The amorphous graphite is that 

 variety to which the terms " plumbago " and " black-lead " are ordinarily 

 applied. It is much softer than the crystalline graphite, and makes a 

 blacker streak on paper. Formerly it was obtained almost exclusively 

 from Borrowdale, in Cumberland, but the mine there is nearly ex- 

 hausted, and we believe is no longer worked. The bulk of that used at 

 present comes from Germany, principally from Griesbach, near Passau. 

 Both varieties are used in the manufactures of the Company ; 

 the crystalline for crucibles, and the amorphous for polishing powders. 

 The consumption of Ceylon graphite at the Battersea Works has had 

 an extraordinary effect upon the price of the article. When the Com- 

 pany commenced business it cost about 10Z. per ton, but now it cannot be 

 bought at double that price. In Ceylon we hear that applications to dig 

 graphite are daily on the increase, notwithstanding the rate of 14s. 

 per ton which has to be paid as royalty at the Colombo Cut- 

 cherry. The following figures, giving the amount of revenue collected 

 at Colombo and Galle, on account of royalty, in 1862 and 1863, clearly 

 show the extraordinary increase in the demand for Ceylon graphite : — 





1862. 





1863. 



Increas e. 





£ s. 



d. 



£ s. d. 



. £ s. d. 



Western Province.... 



. 472 4 



4 



1,272 10 2 



800 5 10 



Southern Province... 



. 112 2 



8 



282 8 5 



170 5 9 



