( 3 i6) 



6992. Thistle cane. — A cane made of the stem of a thistle, probably Cirsium lan- 



ceolatum (L.) Hill (Carduaceae — Thistle Family). Same donor. 

 Following No. 6992, and in the same case, are a number of wood-samples of which 

 the botanical origins are unknown. 



Charcoals 



Vegetable carbon, or charcoal, is the solid residue left 

 after driving off the volatile constituents from vegetable 

 substances by the action of heat, oxygen being mostly 

 excluded during the process. Such charcoal consists 

 chiefly of carbon, but among its particles exist various 

 minerals ubstances, chiefly silica. In proportion to the 

 amount and character of these mineral matters, the proper- 

 ties of the carbon differ, as does its usefulness .for various 

 purposes. In the making of gunpowder, the presence 

 of crystalline silica is liable to generate sufficient heat 

 in grinding to cause explosions and great care must be 

 taken to select woods for such charcoal that are free from 

 such crystals. For burning purposes, the greatest pro- 

 portion of carbon gives the best results. For electric 

 light carbons, a great abundance of particles affording 

 incandescence is requisite. 



Unless otherwise specified, the following charcoals were 

 presented by the General Electric Company. 



6993. Matsu charcoal. — Charcoal from the wood of Pinus densiflora Sieb. & Zucc. 



{Pinaceae — Pine Family). Native of Japan. 



6994. Typha peat. — The natural peat resulting from the remains of Typha angusti- 



folia L. (Typhaceae — Cat-tail Family). A swamp plant of the north temper- 

 ate zone. As a result of pressure and long continued slight heat, partial 

 carbonization has taken place. The specimen is from the shore of the 

 Miami River, Florida, and various other plants are mixed with the cat-tails. 

 Collected by C. F. Sulzer, November, 19 12. 



6995. Mariscus peat. — Peat resulting like the preceding, from the remains of 



Mariscus jamaicensis (Crantz) Britton {Cyperaceae — Sedge Family), mixed 

 with other sedges, grass, etc. Native of the warm parts of America. 

 Collected in the Florida Everglades by C. F. Sulzer, November, 191 2. 



6996-7004. A series of specimens illustrating bamboo stems, formerly used in 

 making incandescent electric light carbons, showing the six successive 

 steps in splitting the bamboo to the necessary fineness. 



6996-7002. Seven splints of different thickness. 



7003. The mounted bamboo carbon ready for insertion in the lamp. 



