1837.] 



FARMERS' REGISTER, 



587 



fired it with a match or candle, it would continue 

 burning till ail were spent. It might be worthy 

 consideration likewise, whether those (i-ecjuent 

 thunders proceeded from the air's being more 

 stagnant, the motion ot^ the winds being imped- 

 ed "by the trees, or whether the motion of the 

 winds beingobstructed by them below, the motion 

 might not be more violent alolt ; and how liu* that 

 may promote inflammability, I'or slacks oi' hay or 

 corn that lerment with moisture, never burn, un- 

 less when brisk winds blow, that agitate unci Ian 

 the little lermcnting sparks, and oiten kindle them 

 into an actual fire. And observance of the me- 

 teors there might perhaps not be impertinent, as 

 both what are more nu'e, and what are more Ire- 

 quent, as of Gosimnre in great abundance, and of 

 those small cobwebs in a morning,^ which some 

 liave supposed to be meteors. Ignes fatui, tho' 

 there be many boggy swamps and marshes, are 

 seldom, if any are seen there. There be frequent 

 little sorts of whirl-winds, whose diameter may 

 be sometimes not past two or three yards, some- 

 times Ibrty, which whisking round in a circle, pass 

 along the earth, according to the motion of the 

 cloud, from Avhence they issue ; and as they pass 

 along with their gyrous or circular motion, they 

 ■carry aloft the dry leaves into the air, which lull 

 again often in places far remote. I have seen 

 them descend in a calm sun-shine day, as if they 

 had come from the heavens in great showers there- 

 of, so that all the elements seem'd filled therewith. 

 And I could perceive them to descend li'om on 

 high as far as I could possibly discern a leaf. I 

 remember a roguish expression of a seamen, 

 otherwise silly enough, who wondering thereat, 

 cry'd out, "Sure now His manifest there is a world 

 above .' and now with them 'tis the fall ot the 

 leaf." But to proceed, I thought this made it man- 

 ifest, wdience many preternatural showers have 

 happen'd. I remember at Sir Richard jJlhertoii's 

 in Lancashire, some i'ew years ago, there fell a 

 great number of the seeds of ivy-berries ; at first 

 we admir'd what they were, for they were co- 

 ver'd with a thin skin that was red, and resem- 

 bled the figure of a small wheat corn ; but after- 

 wards they iully maiiili?sted what they were ; for 

 many sprouted and took root. I suppose they 

 were carry'd aloft by some such whirl-wind, and 

 let fall there. I have purpos^.ly gone into the 

 ))lace where t perceived this gust, which is noto- 

 rious enough by the noise it makes, with rattling 

 the leaves as it carries them aloft, and have found 

 a fine sharp breeze oi' wind. 



[To be continued.] 



From tlie New York Farmer. 

 MECHAIVICAL USES OF LIME. 



Preparation of Quicklime. 



Under the general name of limestones are com- 

 prehendeded all mineral substances which con- 

 tain not less than half iheir weight of carbonate 

 of lime. Quick lime is prepared from most of 

 these limestones, by calcination, and is character- 

 ized by the property of absorbing water with phe- 

 nomena of heat, an action which, if it also cause 

 the lime to fall to powder, is called slaking. Lime 

 prepared from difierent varieties of limestone has 

 different properties in this respect. In some cases 

 the action is rapid and violent, the heat produced, 

 great; in others the operation is more slow, and 



the heat less intense. There are also, lime- 

 stones which alter calcination will not slake. The 

 limestones which are richest in carbonate of lime 

 belong to the first variety ; those which contain 

 carbonate of magnesia in a proportion greater 

 than 10 per cent, to the second; while the resis- 

 tance to the action of the slaking in the third, is 

 due lo the presence of argillaceous matter. The 

 two first varieties are alone suited to the prepara- 

 tion of mortar. The last variety will not make 

 mortar in the usual manner, but is nevertheless of 

 great value as an ingredient in cements which 

 will resist.the action of water. In the act of slak- 

 ing quick lime, which retains, after calcination, the 

 shape and structure of the limestone whence it is 

 prepared, liills, as has been stated, to fine powder. 

 It also fiills to powder after exposure to the air, 

 when it is said to be air slocked. In the first case 

 the lime combines with water forming a solid hy- 

 drate; in the latter it absorbs carbonic acid from 

 the atmosphere, and returns to the same chemical 

 state which the limestone possessed before calci- 

 nation. 



The calcination, or, as it is usually styled burn- 

 ing of lime, is performed in chambers built of 

 stone, which go by the name of kilns. Of these 

 there are two descriptions, ordinary and perpetu- 

 al. The ordinary lime kiln is of the shape of a 

 truncated cone, or of a portion of an ellipsoid. 

 The limestone is prepared for calcination by break- 

 ing it into pieces, none of which have a greater 

 dimension than 3 or 4 in. cube. The large frag- 

 ments of limestone are employed in building a 

 rude vault, over a cavity left in the lower part of 

 the kiln. To this cavity an entrance or door is 

 left in the wall of the kiln. The rest of the kiln 

 is filled up with smaller jjieces. When wood is 

 used as fitel, it is introduced by the door into the 

 space beneath the vault, and is burnt on the floor 

 of the kiln. When coal or turf are employed, an 

 iron grate is provided, on which the fuel is placed, 

 leaving an ash-pit beneath. In building the vault, 

 the spaces betvveen the stones are left of as great 

 an area as possible, and in filling the kiln the lar- 

 gest of the remaining pieces are laid next to the 

 vault, while the smallest fragments are used for 

 covering the rest, and closing the top of the kiln. 



The fire is at first moderate, in order that the 

 limestone may be gradually heated. After 10 or 

 12 hours the quantity of fuel is gradually in- 

 creased, until the mass of limestone is brought 

 nearly to a white heat. After it has been kept lor 

 some hours at this temperature, the bulk of tlie 

 mass of limestone decreases about one-sixth, and 

 flame issues almost free fi'om smoke, from the top 

 of the kiln. The intensity of the heat is then 

 gradually diminished until the fire is permitted to 

 extinguish iiself, for want of fuel. In order to 

 complete the calcination of a given bulk of lime- 

 stone in an ordinary kiln, nearly three times its vol- 

 mne of wood, or twice its volume of turf or coal 

 is required. Much of this quantity of fuel is con- 

 sumed in the gradual heating of the limestone and 

 in preventing it from cooling too rapidly after the 

 calcination is complete. It is therefore obvious 

 that in a kiln in which the operation might be 

 kept up without ceasing, a considerable saving of 

 fiiel might be ensured. Such a kiln is said to be 

 perpetual. The first attempt at the construction 

 of a peq^etual kiln was made by Count Rumford. 



