IMP 



INC 



ILIAC PASSION. A violent col- 

 ic, in which feculent matter is vom- 

 ited. 



ILIUM The haunch hone. 



IM.\GO. The wmired insect. 



IMBRICATED. Ovcrlai)ping, like 

 the shingles of a roof". 



IMPACT. The concussion of one 

 body on anotiier. 



IMPENETRABILITY. An es- 

 sential property of matter, uiicreby 

 one molecule only can occupy a given 

 space at a certain time. 



IMPETUS. The force or momen- 

 tum of a body in motion. 



I.MPER.MEABLE. Rendered wa- 

 ter-proof; this may be done with cot- 

 ton, silk, or other cloths by satura- 

 ting with drying linseed oil ; linseed 

 oil holding in solution India rubber ; 

 a varnish made by dissolving India 

 rubber in naphtha ; by pitch ; a solu- 

 tion of glue applied to cloth, which is 

 afterward dipped in infusion of galls. 



Impermeable, in physics, also means 

 capable of resisting the passage of 

 gases as well as fluids. 



IMPINGE. To strike upon; a 

 word much used in optics to express 

 the incidence of light. 



I M P L E M E N T S. Suitable care 

 should be taken in keeping them free 

 from rust and unnecessary exposure ; 

 parts subject to movements should 

 be kept oiled, and the whole stored 

 in a drv place in the barn. 



IMPONDERABLE. A term used 

 to express light, heat, or electricity, 

 which are destitute of any discovera- 

 ble weight. 



I.MPOSTHUME. An abscess. 



IMPREGNATION. Conception. 

 In horticulture, the contact of pollen 

 Willi the stigma is called impregna- 

 tion ; without this, no seed is pro- 

 duced. Artiticial impregnation is 

 called hybridizing. See Hybrid. By 

 it numerous choice fruits, vegetables, 

 and flowers have been produced. 



I M P R OVE M E NT OF LANDS. 

 See Barren Landaud Arable Land. 



IMPROVE.MENT OF PLANTS. 

 The chief means are manuring, care- 

 ful tillage, proper exposure to sun or 

 shade, pruning, summer pruning, hy- 

 bridizing, securing line seeds. Im- 



proved varieties are maintained by 

 grafting, slips, partuig the roots, and 

 high culture; without the latter, an- 

 nuals degenerate. Nature often vol- 

 unteers an improvement, which the 

 orchardist should at once avail him- 

 self of by propagation, and by care- 

 fully collecting the seeds. In this 

 way several varieties of wheat, or 

 other plants, sown together occa- 

 sionally, exhibit a new kind, superior 

 to the rest, the seed of which must 

 be carefully separated and sown alone 

 on excellent soils. 



INANITION. A state of languor, 

 emptiness. 



INARCHING. A kind of grafting, 

 in which the scion is not cut from its 

 parent, but the scion and stock are 

 made to come together at a certain 

 place ; they are then both pared down 

 to the new wood, and a tongue made 

 in each wound, so as to enable 

 them to fit closer ; the two are then 

 bound together (the parts being ad- 

 justed) by bass and grafting clay, and 

 supported by a stake driven in the 

 ground. The plants should be sha- 

 ded, most of the buds removed, and 

 the stock headed down nearly to the 

 scion. When the parts are firmly 

 united, which requires three or four 

 months, the scion is cut from its pa- 

 rent. This process is sure, but troub- 

 lesome. The scion may be some- 

 times a slip, the heel of which is kept 

 in water. The operation is perform- 

 ed in April or May, and usually on 

 jessamins, myrtles, camellias, wall- 

 nuts, and firs. 



INCANDESCENCE. A luminous 

 heat. 



INCANUS. Hoary ; covered with 

 a whitish down. 



INCH. The twelfth part of a foot. 



INCIDENCE. The meeting of one 

 body with another. The angle of in- 

 cidence is formed by the direction of 

 the light to a line perpendicular to 

 the plane of the surface on which it 

 falls. 



INCINERATION. Burning to 

 ashes. 



INCISED. Cut with a sharp knife. 



INCISIONS IN TREES. Draw- 

 ing a sharp knife through the bark 



415 



