204 



NKW ENGLAND FARMER, 



Jan. 16, 1829. 



From (he Richmond Enquirer. 



ON GYPSUM— AND ITS USES IN AGRI 

 CULTURE. 



Gypsum, or Plaster, as it is commonly called, is 

 a kind of earthy salt, composed of lime, sulphuric 

 acid and water. When jjure, these ingredients 

 enter into its composition in the following propor- 

 tions, in each 100 parts, viz. 



Lime, . . . 32 to .34 

 Sulphuric acid, . . 46 to 4S 



Water, . . . 22 to 18 



100 



100 



Besides the various uses to which it is applied 

 in the arts, it is an article highly recommended in 

 agriculture as a great fertilizer of the soil and pro- 

 moter of vegetation. 



It is in this latter view that the writer of the 

 following remarks wishes it to be considered, be- 

 ing well satisfied that it deserves the particular 

 attention of the citizens of Virginia, and more es- 

 pecially of those in the middle and lower sections 

 of the state, where their lands have been cultivat- 

 ed generallj' with less care, in regard to their pre- 

 servation, and are considerably more deteriorated 

 and exhausted than those in the valley and jnoun- 

 tain country. 



It is employed by agriculturists in a variety of 

 ways, and always with the happiest eflects, when 

 pr-re and properly applied. It is sometimes sown 

 over cultivated grasses, grain and other vegeta- 

 bles, as a top dressing. Grain and seeds, after 

 having been moistened, are often rolled in it, pre- 

 vious to their being sown or planted. And, oc- 

 casionally, it is dropped in the hills with corn, &c. 

 In the ai)plication of it, as a top dressing, atten- 

 tion should be paid to the times, season of the 

 year, and growth of the plant ; choosing a close, 

 still, dani]) day, or still foggy morning, as the 

 wind blows it about too much, and in dry weath- 

 er it is not apt to stick well to the plants. Some 

 are of opinion that the best time to dress young 

 clover, .sown down on grain, with it, is when it 

 gets three leaves ; others advise to defer it till the 

 grain is cut off. For old clover, the best time ap- 

 pears to be as soon as vegetation commences in 

 the spring. Tobacco should be dressed with it 

 when the plants begin to spread tlie hill, and corn, 

 when about half a leg or knee high. 



When it was first introduced among us as an 

 article of agriculture, the very high, encomitmis be- 

 stowed ui)on it, and the almost incredible ac- 

 counts related of its wonderful effects on vegeta- 

 tion, induced many of our farsners and planters to 

 engage in the use of it, fondly hoping, no doubi, 

 that with the aid of clover and plaster, they would 

 be enabled, in a few years, to resuscitate their 

 worn out and exhausted soils, and impart to them 

 a degree of fertility equal, if not superior, to what 

 they originally possessed. But the result of our 

 experiments has not been such as to sustain the 

 exalted character it had acquired. For, although 

 in some instances its effects were truly astonish- 

 ing, its operation in general appears to have been 

 very uncertain. And we have often had the mor- 

 tification to witness, after having encountered 

 nuich trouble and expense in ])rucuring and aji- 

 plying it to our crop, tluit it was jiroductive of no 

 perceivable beneiit. A consequence so discour- 

 aging seems to have brought it soinev/bat into dis- 

 repute. So that, far from being in general use at 



this time, as might have been expected, even those 

 few who thought well of it at first, and were anx- 

 ious to bring it into notice, have themselves be- 

 come, in some measure, disgusteil with it, and 

 there are even some grounds to apprehend, unless 

 something sliall be done to restore it to confi- 

 dence, that it will ultimately be abandoned alto- 

 gether. A misfortune the more to be deplored, 

 because nothing is more certain than that, when 

 pure and juiliciously applied, there is not a great- 

 er fertilizer known. And, indeed, without the aid 

 of some such powerful substance, it is believed to 

 he utterly imijracticable, after the lajjse of a long 

 series of years, so to improve our lands as to give 

 to them that degree of fertihty of which they are 

 susceptible. 



To trace this uncertainty in its operation to its 

 .source, and to point out the means by which in 

 future it may be avoided, would be to re-establish 

 it in the public confidence. As our planters aiKl 

 farmers would, undoubtedly, freely employ it, 

 could they be well assin-ed that, in laying out 

 their money in the i)urchase of it, they would no 

 longer be subjected to the hazard of a disappoints 

 ment. This will now be attempted. 



It has already been stated that gypsum wag 

 composed of lime, sulphuric acid and water. And, 

 by an attention to the relative proportions of each, 

 it will be seen that, wdien pure, the sulphuric acid 

 amounts to nearly half its weight. 



The quantity usually sown on an acre, is a 

 bushel, in which, as a bushel of ground plaster is 

 said to weigh about eighty pounds, there would 

 be 



Of Lime, . . 25.60 lbs. 



Sulphuric acid, . . 36.80 



Water, . . . 17.60 



80.00 



Now, it must be obvious that 25.60 lbs. of lime, 

 which would amount to little more than a peck, 

 could not possibly produce any visible effect when 

 spread over an acre of land. The quantity of wa- 

 ter (17.60 lbs.) would be next to nothing ; and 

 that, therefore, all the operative virtue of the arti- 

 cle must reside in the sulphuric acid. 



Hence it may rationally be inferred that, gen- 

 erally s])eaking, whenever the plaster fails to act, 

 it is in consequence of a deficiency in due propor- 

 tion Of this latter ingredient : an idea that will re- 

 ceive iiuich countenance from an examination of 

 its properties, some of which will be found pecu- 

 liarly adapted to the promotion of vegetation. — 

 Such as its capacity for attracting moisture from 

 the atmosphere — and, when combined with it, of 

 generating heat. Thus affording, in itself, two of 

 the ibur great essentials. For, whatever may be 

 the opinions of some philosophers respecting the 

 gaseous and ethereal elements of vegetation, in 

 practice it is found that nothing more secjns to be 

 necessary, in addition to soil of a proper texture 

 and judicious cultivation, than light, heat, air and 

 moisture, distributed in due jn'oportions. 



It would certainly be highly proper that the le- 

 gislature should extend the benefit of the inspec- 

 tion laws to the article of plaster, and establish iti- 

 spections of it at suitable places, not only as af- 

 tording relief and security to the purchaser, but 

 as a measure of precaution, it being understood 

 on good authority, that much of the refuse gyp- 

 sum at the north, where they have inspections es- 



tablished, is ground up and sent to the south, by 

 fraudulent dealers in the article, for sale. 



lint, in the mean time, to enable those purchas- 

 ers who are not conversant with it, to judge at 

 once of its purity, without the possibility of being 

 deceived, it is deemed proper to state that nitrous 

 acid, conmionly called aqna fortis, forms an uner- 

 ring test. They have only to drop a small quanti- 

 ty of it on the plaster, (whether ground or in the 

 rock, makes no difference,) and if it causes an ef- 

 fervescence — a foaming and frothing similar to 

 what is observed when strong vinegar is poured 

 upon chalk, it is a proof of its impurity. And the 

 degree of impurity may be pretty well ascertained 

 by the mildness or vehemence of the efferves- 

 cence. 



Lime has a great affinity ibr all, or most of the 

 acids, whether mineral or vegetable, and will ef- 

 fervesce with any of them. But its attraction for 

 the sulphuric acid is much moie considerable than 

 tor the nitrous acid, and, therefore, when fully sat- 

 urated with the former, the latter can exert no in- 

 fluence on it. For it is a law of chemical action, 

 that two substances having an affinity for each 

 other, being brought into contact, under suitable 

 circumstances, they will unite and combine to- 

 gether in such a manner that they cannot be 

 again separated, but by the presence and inter- 

 vention of some third substance, having a greater 

 affinity for one of the combined bodies than they 

 have for each other. 



When, then, the nitrous acid is perceived to act 

 upon the gypsum, it is a proof that the sulphuric 

 acid not having been in a quantity sufficient com- 

 pletely to saturate the lime, it has only been par- 

 ~V?'^tially converted into gypsum, and that a portion 

 still remains unchanged, which is the part acted 

 upon by the niti'ous acid. 



In whatever way the plaster may be applied to 

 crojjs, it must first undergo decomposition. For 

 so long as it remains undecomposed, the sulphuric 

 acid, the operative material, will be neutralized by 

 the lime, and will not be in a condition to act on 

 the atmosphere, and the plaster will have no more 

 effect than so much sand, or a like quantity of 

 any other pulverized rock. 



By what the decomposition is caused, it is diffi- 

 cult to determine ; but that it is something, prob- 

 ably carbonic acid, derived from the air, is render- 

 ed highly probable from the circumstance that it 

 will remain inoperative if buried too deep under 

 ground. That it is an acid, and acts altogether 

 on the lime, is obvious, otherwise the sulphuric 

 acid would not be set free in a perfectly disen- 

 gaged state, but would only enter into a new com- 

 bination, be neutralized as before, and remain per- 

 fectly inactive. 



The best effect of plaster .seems to be as a top 

 dressing, used on dry land, and in cool dry weath- 

 er ; as in very wet seasons, and on low, flat, wet 

 land, its influence is not very discoverable. 



As to the modus operandi, or manner in which 

 plaster acts, it appears to be very generally im- 

 lagined that it possesses the power of stimulating 

 the earth into preternatural action, and that, how- 

 ever beneficial it may be ot first, it will ukimate- 

 ty, by long continued use, produce exhaustion, and 

 lause more injury than ever it did good. An 

 bpinion, probably growing out of the fact that a 

 iong and unremitted use of it brings about that 

 condition of the soil denominated " plaster-sick." 



The subscribers to this doctrine seem to consid- 

 er the earth somewhat in the light of a lazy, slug- 



