No. 31.— 1885.] 



PLUMBAGO. 



225 



method of preparing it was not known till within a few years, and 

 it comes upon the market now little understood, and almost like a 

 new material. It is destined to work great changes. Mixtures 

 and quack nostrums are sold with sounding names, but as the 

 plumbago in them is all they contain of the least value, it is 

 better to use it pure." 



I notice, however, from advertisements in the American 

 papers, that u mica grease" as a lubricator is competing with 

 plumbago, but how far successfully I cannot say. What I 

 know is that the writer of a recent article on American 

 minerals strongly supports Mr. Cleveland's view as to the 

 great superiority of plumbago as a lubricator. I am not 

 aware that it is so used to any extent in Ceylon, either 

 in foundries or on the railways, although if all stated 

 regarding its value be correct, Ceylon plumbago ought to 

 be much more largely used in Ceylon than it is at present, 

 as a lubricant and for other purposes. For all uses it 

 would seem that grinding to extreme fineness is essential. 

 Mr. Cleveland proceeds : — 



" Electrotyping. — To the electrotyper absolute purity in his 

 plumbago is a necessity, and hence any adulteration will discover 

 itself at once on trial. The purest selected Ceylon lumps should 

 be treated as described for lubricating, but the separating process 

 should be carried to a finer point, and the acid bath given with 

 care. This acid should be applied till with a thorough stirring no 

 effervescence takes place, or bubbles rise to the surface. In 

 electrotyping the great conducting power of the plumbago asserts 

 itself." 



Mr. Cleveland, it will be observed, speaks of plumbago 

 as if it were invariably a good conductor, but another writer 

 on the subject (Smee), who seems to write from experience, 

 says that some lumps are non-conducting, just as some 

 pieces though perfectly pure carbon are so hard as to resist 

 the saw. And now we come to a use for plumbago, scarcely 

 if at all inferior to that of crucible manufacture, viz. : — 



Facing for Moulds or Foundry Facings. — For this purpose 

 plumbago is but little understood, although it is used to a limited 

 extent. That it is valuable, most skilful moulders are aware ; 

 consequently, much of the trash that is sold for ' facings' is called 

 plumbago, to make it sell, without containing a particle of 



