OF CENTRAL CANADA PART II. 61 



I. SIMPLE SUBSTANCE. 



[This group includes the Native Non-Metallic Elements and Native 

 Metals of Canadian occurrence. Three of these, Graphite, often 

 termed Plumbago or u Black Lead," but consisting essentially of 

 carbon, Native Gold, and Native Silver, are entitled to rank amongst 

 the economic products of the country ; and Native Copper may even- 

 tually perhaps be added to the .list. The rest occur in small quantities 

 only, or under more or less obscure conditions.] 



A. NATIVE NON-METALLIC SUBSTANCES. 



1. Graphite (Plumbago) : Iron-black or dark steel-grey, with black 

 lustrous streak, and metallic or sub-metallic aspect. Found occasion- 

 ally in tabular hexagonal crystals, but more commonly in small scales, 

 and in foliated and granular masses, which soil the hands, and leave 

 a dark metallic trace on paper. Very sectile, and greasy or soapy to 

 the touch. H = 1.0 2.0; sp. gr. 2.0 2.3 in pure specimens, 

 but sometimes as high as 2.5. BB, quite infusible, and not dissolved 

 by borax or ordinary fluxes. Consists essentially of carbon, with a 

 variable amount of intimately intermixed siliceous or ferruginous 

 matter, the so-called f< ash." This, which becomes visible when the 

 carbon is burnt off by long continued ignition, may vary from a mere 

 trace to 40 or 50 per cent. The actual amount of ash scarcely affects 

 the value of the plumbago. Samples holding 40 or more per cent, 

 may possess as much marketable value as others in which no more 

 than 8 or 10 per cent, is present. But a great deal depends on the 

 composition of the ash, at least as regards certain uses. If the ash 

 contain more than a very slight amount of lime or magnesia, the 

 graphite is scarcely suitable for the manufacture of crucibles. A 

 selected sample, from Buckingham, on the Ottawa, shewed the follow- 

 ing composition : 



Carbon 80.12 f Silica 12.86 



Alumina 4.33 



A _i, 10 KOI Iron Oxide 1.07 



Ash 18 - 58 ]Lime... , 0.16 



| Magnesia trace 



Moisture 1.30 I Loss 0.18 



Another sample yielded : moisture 1.14, ash 22.06, carbon 76.80. 



In the form of small scales and flaky masses, graphite is widely 

 disseminated throughout the area occupied by the Laurentian series 

 of rocks (Part Y.) It occurs most commonly in the beds of crystalline 

 limestone of this series ; but sometimes also in the gneissoid strata, 



