(316) 
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, 1912. 
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, 1912. 
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. 
