eo2 



FARMERS' REGISTER— EXPOSURE OF GYPSUM. 



timately centre (and that at no distant day) in that 

 great Valley. And I for one, will hail that era as 

 one of the brightest lor t]\e agricultural prospects 

 of middle Virginia, Already', nearly all our best 

 lands have been cut down, in cultivating this ruin- 

 ous crop, and hence, it becomes manifest, that we 

 cannot be, to any extent, a tobacco making peo- 

 ple. Let us then, curtail our crops, improve our 

 lands, husband our resources, and with the smiles 

 of providence, and the approbation of our own 

 consciences, we shall be a prosperous and happy 

 people, enjoying a climate, exempt trom the ex- 

 tremes oi' heat and cold, and the truits of a soil, 

 susceptible of as a great a variety of products 

 as any on the habitable globe. Then, and then 

 only, will we deserve well of posterity, and im- 

 prove the talents so bountifully committed to our 

 care. 



IVardsfork, Charlotte County. g. 



INQUIRIES AND REMARKS ON THE EFFECT 

 OF EXPOSING GYPSUM TO THE WEATHER. 



Valmont, Jan. 23, 1835. 



"to the Editor of the Fanners' Register. 



i have a parcel of Plaster of Paris which has 

 been several months exposed in hogsheads to all 

 the vicissitudes of weather, wet and dry, hot and 

 cold, even to freezing. It is the leavings of a 

 plaster yard, and this not completely ground, is 

 mostly in a sandy state with some lumps; these 

 lumps will crumble more easily than the lumps as 

 we first receive it. I want to know whether it has 

 totally lost its \nrtue, or to what extent, by expo- 

 Bure; and whether in preparing it lor use, it would 

 be proper to dry it^^over the fire — fcr it is quite wet, 

 and seems very unwilling to surrender its mois- 

 ture. As lime is one of its components, I presume 

 it has been partially slaked, and is therefore more 

 or less weakened. I have subjected it to one test 

 which seems to indicate that it is not entirely de- 

 stroyed. By heating, and then pouring water upon 

 it, it runs together and forms quite a hard cement. 

 For want of pot or pearl-ash I cannot try it by 

 boiling with that, nor have I the means of deter- 

 mining whether the residuum would be carbonate 

 of lime. When plaster is scattered over the earth 

 it is immediately liable to this slaking process, 

 (if it may be so called) and ?S.ll the effects of sun, 

 air, and rain: and universal experience I believe 

 .attests, that it is slow and continuing in its ac- 

 tion, not producing its effect by any sudden and 

 powerful impulse. Its action is so slow, that we 

 have a right to suppose it is going on a long 

 time — for months or years — long after the weaken- 

 ing effects of weather upon it have taken place. 

 The result of an experiment at Dover, communi- 

 cated some years ago to the Agricultural Society 

 of Richmond, proved that the efl'ects of plaster 

 were visible fourteen years, I think, after the plas- 

 ter was applied: and that I witnessed myself. The 

 slow operation of plaster, results from its modus 

 operandi, whether as an absorbent, by drawing 

 and retaining moisture around the plant, or as a 

 solvent, by preparing vegetable matter for its food. 

 The only difference then, between the application 

 of plaster in its fresh state and in that which I 

 have supposed, is in the point of time whilst (in 

 the first state) the dissolving or slaking process 

 occurs. Now, what is the value of that differ- 

 ence? 



I will trouble you with another question, whilst 



we are upon the subject. If plaster acts merely 

 as an absorbent, of what consequence is the na- 

 ture of the soil, provided it is loose enough to allow 

 the powder to descend to the roots, and not so 

 loose as to allow it to pass below them ? If as a 

 stimulant in any other way, why should not a 

 moist soil be as sensible of its effects as a dry one, 

 provided it is not so wet as to carry off the pow- 

 der? Would you advise lime or plaster in a wet 

 piece of ground — it being presupposed that ail 

 practicable means have been used to drain it ? — for 

 I believe it ma}' be considered an axiom in 

 agriculture, that lor whatever purpose land is in- 

 tended, it must be laid as dry as possible. 



If Mr. Editor, interrogatories generally betray 

 ignorance, much more do they in this particular 

 case — and taking to myself the compliment once 

 paid to Pope, I might with pro])riety subscribe 

 myself a '? But not having pride enough to hide 

 my ignorance, I give you my proper appellative, 

 which you will recognize to be that of an old 

 fellow-collegian. 



C. H. HARRISON. 



[ The foregoing inquiries proceed from one who has 

 had far more piacfical experience of the use and ef- 

 fects of gypsum than we have gained — and if that 

 mode of observation and of proof alone were to be tlie 

 proper test, we ought to take refuge in our want of ex- 

 perience, and remain silent. But as most of the an- 

 swers sought, must depend altogether upon the estab- 

 lished chemical properties of the substances in question, 

 we can scarcely eiT in deciding according to tliose pro- 

 perties: and the remarks which follow will be confined 

 witliin such limits as will prevent our losing sight of 

 this sure guide — without which, none will fail to wander 

 into uncertainty and error. 



The slaking of quicklime, alone, is no cause of in- 

 jury, or weakening of its power — but as this pro- 

 cess always precedes or accompanies the injury which 

 is really caused by exposure to air, the slaking of lime 

 is generally considered as evidence of some progress at 

 least having been made in the lime's becoming carbona- 

 ted, effete, or mild, or losing its peculiar qualities as caus- 

 tic lime. The newly burnt material for lime, (as shells 

 or limestone,) greedily attracts moisture, and by uni- 

 ting chemically with water alone, it slakes, but still re- 

 tains all its caustic power, which depends not on the 

 absence of water, but upon the deprivation of car- 

 bonic acid, which the lime had lost by burning. This 

 acid next commences re-combining with the lime, to 

 which it is strongly attracted, and is furnished by the 

 atmosphere, and as well as by the earth, and by plants 

 and other matters in a state of decomposition — and 

 this process of re-combination is greatly hastened by 

 the lime having been slaked, and thereby exposing a 

 far greater attracting surface. Of course, the more it 

 is spread to the air, or to whatever will furnish car- 

 bonic acid, the more rapidly the lime loses its caustic 

 quality, until none remains. The lime now, as car- 

 bonated or mild, may be in most cases, as valuable a 

 manure as when quick, (as we have elsewhere endeav- 

 ored to show) — but as a material for cement, and for 

 every purpose for which its caustic state was essential, 

 the lime is weakened and indeed destroyed, by being 

 changed to a different chemical substance. 



