COM 



CON 



disease or stupidity. Comatose is a 

 derivative. 



COMBINATION. In chemistry, 

 the chemical union of atoms, wlicrc- 

 by the scnsiljlc jiropcrtios of the com- 

 bining parts are altered. It takes 

 place in nialhematical proportions. 

 See Atom. 



COMBUSTION. Burning. The 

 chemical change of a body, attended 

 with heat or light. For combustion, 

 the body must be surrounded with a 

 medium which enters, in part, into 

 the change, such as oxygen, chlorine, 

 &c. 



COMFREY. The Symphytum offi- 

 cinale, a rough perennial plant, with 

 coarse, rough leaves and large roots. 



' COMMISSURE. In anatomy, a 

 junction or union. 



C O M O S E. Ending in a tuft or 

 brush, like the top of a tree. 



COMPASS. An instrument used 

 by mariners and surveyors to obtain 

 the bearing of any place. The essen- 

 tial part is a magnetic needle, which 

 plays over a card marked into the 

 points of the compass. The follow- 

 ing figure gives the full divisions : N 

 signifies north, S south, E east, \V 

 west, and b by or towards. 



The American Agriculturist thus 

 writes : 



" We learn by the Portsmouth 

 Journal that Mr. Robinson is of 

 opinion, from an imperfect experi- 

 ment made by him on a small patch 

 of ground, that he will be able next 

 year to gather, at two cuttings, eight 

 tons of leaves of the comfrey root to 

 the acre, which, he says, is excellent 

 food for stock. The root is consid- 

 ered very nutritious for man or beast ; 

 and Mr. Rich, of Troy, N. H,, asserts 

 that it can be harvested every two 

 or three years, and will yield over 

 2000 bushels per acre. We should 

 tliink it advisable to try the experi- 

 ment of a rod or two square of grow- 

 mg comfrey in this vicinity. It is 

 cultivated by transplanting the roots, 

 which grow wild in the fields, to any 

 ground deep ploughed and well pul- 

 verized." 



172 



4. ^ 



•/'. 











COMPOSIT.E. Plants like the 

 sunflower, dandelion, lettuce, &c., 

 the flowers of which are grouped to- 

 gether on a flattish surface. They 

 are very numerous, and form the 

 Syngcnesia of Linneeus. Few are cul- 

 tivated ; most are valueless weeds ; 

 but chamomile, wormwood, and a 

 few others yield bitter medicines. 

 Their ashes abound in potash. 



COMPOST. Any compound of 

 manures, usually of vegetable matter 

 for the most part. See Peat, Lime, 

 Vesetahlc Matter, &..Q. 



COMPRESSIBILITY. This qual- 

 ity depends on the natural pores of 

 bodies, which enable the solid parts 

 to approach nearer under great force. 



CONCAVE. Having a hollowed 

 surface. Concave surfaces in mir- 

 rors produce a magnifying effect, and 

 condense heat and light. 



CONCEPTACLES. Theseed 

 cases of ferns, lichens, &c. 



CONCHOID (from Koyxrj, a shell). 

 Like a shell. The name of a curve. 



CONCRETE (from concrcscere, to 

 coalesce in one mass). In architecture 

 and engineering, a mass composed of 



