CHL 



CHO 



when harvested, is nearly worthless 

 and the straw vastly injured. By the 

 time the wheat is cut, the bugs (then 

 flies) take wing, and immediately 

 spread over the neighbouring corn- 

 fields, concealing themselves under 

 the blade slips, under the roots, dec, 

 where they dcposite millions of eggs, 

 which are hatched in eight or ten 

 days, and continue through rapidly 

 succeeding generations to prey upon 

 the sap as long as anything green re- 

 mains upon the stalk, finally taking 

 shelter for the winter under the bark 

 of stumps and logs, under large clods, 

 &c., to be ready for the work of de- 

 struction the next season. When 

 first hatched, they are very small, and 

 red as cochineal. They grow very 

 rapidly, and in a week attain half the 

 size of a bedbug ; in a week more, 

 they acquire wings, fly, and spread 

 themselves over the field, depositing 

 their eggs generally. They are, in 

 the last state, about twice the size of 

 a flea, have white wings, and tlieir 

 bodies being dark, have a speckled 

 appearance. I have been thus minute 

 in describing these insects, because I 

 observe they have never been seen 

 in Maryland." Their destruction is 

 attempted by running ditches across 

 the field, filled with straw, and, as 

 soon as the bugs are seen thereon, 

 setting fire to it. The bugs come 

 from forests, and are destro3-ed by 

 occasionally burning the dry leaves. 



CHIVES, or GIVES. Allium sckce- 

 noprasum. A small species of onion 

 growing in tufts. It is propagated 

 by dividing the roots, set out in May 

 and June eight inches apart, and eight 

 or ten offsets together. Keep free 

 from weeds. The leaves may be used 

 for soups. In the fall, as soon as the 

 tops die, dig the chives and store for 

 winter. 



CHLORINE (from ;^:?.upof, green). 

 A green - coloured elementary gas, 

 produced artificially. It is pungent, 

 poisonous, and of great chemical ac- 

 tivity. It exists only in combination 

 in nature : equivalent 35 45. When 

 combined with metals the substances ! 

 are called Cklondcs, as chloride of ■. 

 sodium (common salt), chloride of hy- ; 

 O 



' dro^'en (muriatic acid). The latter is 

 a powerful acid, much used in the 

 j arts, and known under the name of 

 ! spirits of salts. Chlorine also unites 

 with lime and soda, forming feeble 

 compounds, the chlorides of lime and 

 soda ; these, especially the former, 

 are extensively used in bleaching, 

 from the continual escape of the chlo- 

 rine. They are also disinfecting for 

 the same reason. Chlorides are oft- 

 en erroneously called Muriates. Chlo- 

 rine unites with five equivalents of 

 oxygen, and forms the Chloric Acid. 

 One of its salts, the chlorate of pot- 

 ash, is of great value in the arts 



CHLORITE. A mineral of a green- 

 ish colour, common in slates, &c. It 

 is chiefly a silicate of magnesia and 

 iron. 



CHLORO. In chemistrj', a prefix 

 to substances containing chlorine, as 

 chloro-carbonic acid, &c. 

 *CHLOROPIIYL (from x^<^po? and 

 (pv?.?.ov, a leaf). The green colouring 

 matter of leaves. It closely resem- 

 bles wax, and is converted in the fall 

 into a true yellow fat. The presence 

 of chlorophyl is essential to the 

 healthy functions of the leaf, which 

 ceases to absorb carbonic acid from 

 the air when yellow or red. The au- 

 tumnal tints of leaves depend on a 

 change of this colouring matter, the 

 yellow being called Zanthophijl, and 

 the red Erythrophjl. Chlorophyl is 

 also called chromule by some authors. 

 The tints of many flowers depend 

 upon its compounds, w-hich assume 

 every variety between reds, yellows, 

 and greens. Chlorophyl has been 

 veiy recently shown to be analagous, 

 in its phvsical characters, with indigo. 



CHLORURETS. The old name 

 for Chlorides. 



CHOCOLATE. A preparation 

 made by triturating the roasted cocoa 

 beans at a temperature of 130^ Fah- 

 renheit, and mixing with cinnamon, 

 cloves, vanilla, or other spices. 



CHOKE DAMP. The suffocating 

 vapour existing in the bottom of wells, 

 cess-pools, and mines of wood coal. 

 It is an air containing much carbonic 

 acid, and may destroy life. Free 

 exposure to pure air and artificial 



157 



