No. 31.-1885.] 



PLUMBAGO. 



217 



"Crucibles have been in use for melting and refining metals from 

 that distant point of time when man exchanged his stone hatchet 

 and bone chisel for implements of bronze. The earliest melting- 

 pots were doubtless made of the plastic and infusible substance, 

 clay, and there is no reason to suppose that they differed essen- 

 tially from the earthen crucibles now commonly used in our 

 foundries. 



" The works of the Patent Plumbago Crucible Company cover 

 a large space of grouud at Battersea, and have good river front- 

 age. As we proceed along the lane which leads from near 

 Battersea-bridge, we fiud that the grouud gets blacker and blacker, 

 and before we reach the threshold of the office we notice the 

 familiar black-lead polish beneath our feet. Passing a regiment 

 of clerks, we eater the private office of the manager of the works, 

 where we put on a very large coat and a very old hat, which are 

 kept for the use of clean visitors. There are many things in this 

 little office which attract our attention. The walls are covered 

 with testimonials from British and foreign mints respecting the 

 excellence of the Company's manufactures, with here and there a 

 prize medal. The International Exhibition of 1862 is recalled, not 

 merely by the prize medals awarded to the Company for crucibles 

 and black leads, but also by the splendid collection of samples of 

 plumbago, which formed such a striking feature in Class I. In 

 this collection every quality of plumbago is represented by speci- 

 mens from all the most celebrated mines, particularly those of 

 Ceylon, Germany, Spain, Siberia, Canada, Finland, and Borrow- 

 dale. We learn from the manager that some of the samples 

 would not be adapted for the manufactures of the Company. 

 The Siberian plumbago, for instance, contains too much iron ; 

 and, although this could be entirely removed by the Company's 

 patented process for purifying plumbago, it is found cheaper 

 to work with the Ceylon plumbago, which contains but little 

 iron. 



"Before we leave this snug office for the busy factory, we will 

 jot down 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 4 black 

 lead' as an appropriate name for this substance. In most diction- 

 aries graphite is defined as ' carburet of iron,' in accordance with 

 the opinion formerly held by most chemists that it was a com- 

 pound of carbon and iron. This definition is now known to be 

 incorrect ; for although iron is generally present in graphite, it 



