SOS 



FARMERS' REGISTER— GYPSEOUS EARTH. 



lure of these crystals was not suspected before 

 1817, when some person better acquainted with 

 the subject, supposed them to l>e pure gypsum. 

 The expression of this opinion attracted some no- 

 tice at that time, but was received with general 

 incredulity, founded upon the supposed impossi- 

 bility of gypsum cxisling in this region, where it 

 had never been heard of before. A lump was sub- 

 mitted to the inspection of a French apothecary 

 in Petersburg, who had" chemist" painted on his 

 sign : he at once pronounced that the substance 

 was not gypsum, but isinglass. 



The interest which I had felt with regard to this 

 substance was soon after much increased by find- 

 ing some small specimens on my own land, (Cog- 

 gin's Point.) Having no prospect of having the 

 question decided by any person possessing a scien- 

 tific acquaintance with the sul)ject, I consulted 

 books, and found such instruction as enabled me 

 to analyze the sul)stance, and ascertain tliat it \vas 

 pure sulphate of lime, or gypsum. But however 

 satisfactory to myself, it must be confessed that my 

 chemical proof was not much valued by others ; 

 because it was thought impossible that a process 

 believed to be so mysterious, could be accu- 

 rately performed by one who confessedly was 

 ignorant of chemistry, and who had only resorted 

 to its aid for this particular object. To settle all 

 these doubts, I sent collections of choice specimens 

 to two of the most distinguished chemists in the 

 United States, with the request that they would 

 give their testimony as to the nature of the sub- 

 stance. To have complied fully with my wish 

 would not have required fifteen minutes of the va- 

 luable time of either of those gentlemen : yet nei- 

 ther paid the slightest attention to the subject, nor 

 even returned my specimens. These were cer- 

 tainly the strongest among the very many proofs 

 I have known of how little aid chemists are dis- 

 posed to offer to agriculture. As these applica- 

 tions had been made to remove the doubts of 

 others, and not mine, and to attract the public at- 

 tention to what I considered an interesting and per- 

 haps important subject, the results did not discou- 

 rage the progress of my own investigations. 



I had previously ascertained that the gypseous 

 formation was of much greater extent and impor- 

 tance, than the crystals alone would indicate. In 

 all the different places where the crystals had been 

 found, they were imbedded in the same kind of 

 earth, having a very peculiar appearance, and 

 which extended along the south river bank, with 

 but few interruptions, from Bay ley's creek toCoo-- 

 gin's Point, a distance of eight or ten miles.— 

 Having so marked a guide for examination as this 

 earth presented, I found gypsum in it in various 

 places, but in such small quantities, that alone it 

 would never have attracted observation. It was 

 evident that gypsum either was, or had been at 

 some former time, diffused through the whole body 

 of this earth, and therefore I distinguish it by the 

 general name of gypseous earth, although in most 

 cases there may be no gypsum now remaining. This 

 term of course is not always indicative of the pre- 

 sent constitution of the mass. The gypseous earth is 

 of a dull greenish color, mottled with streaks of 

 bright yellow clay. Where gypsum is visible, it is 

 generally in numerous small crystals ; sometimes ni 

 coarse white powder. At one spot only (where 

 first discovered) are the crystals large. Here they 

 are sometimes several pounds in weight, and of va- 



rious and beautiful forms. Some are as transpa- 

 rent as glass: but generally, they are of a dark 

 grey color, owing to a small quantity of dark 

 earthy particles being enclosed l;etween the lamince 

 of the crystals. Except at this place, the solid 

 crystals seldom exceed ten or twelve grains in 

 weight, and generally are less than one grain. 

 The most usual appearance in which they are pre- 

 sented on the bank, is that of a star, formed by nu- 

 merous rays (each a solid crystal) shooting out 

 from a common centre. As these rays are very 

 slightly attached to each other, they generally fall 

 asunder when removed. 



In much tlie greater part of the gypseous earth 

 which has been yet examined, no gypsum is visi- 

 ble ; nor is it believed that even the smallest parti- 

 cle remains. But v*'hetlier gypsum is present or 

 not, the earth is filled with .numerous hollow forms 

 or impressions of shells, so as to prove that this 

 was once part of a bank of fossil shells, (or marl 

 as it is here called,) of which the upper part, un- 

 chaiTged, still forms the cover of the gypseous 

 earth, through its whole extent. The yellow clay, 

 before spoken of, is very often presented in the 

 form of shells, as if, when fluid, it had filled their 

 vacant places. Masses of hard marl, coated over 

 with crysfalized gypsum, are also found here and 

 there in the gypseous earth. A close examination 

 of the bed, and comparing the irnpressionsof shells 

 with the appearance of those still existing in the 

 upper stratum, or in the neighborhood, will leave 

 no doubt on the mind of the observer, of the change 

 having taken place from a bed of fossil shells to 

 gypseous earth. 



This conclusion is attended with two difficul- 

 ties : In tl>e first place, we are at a loss to know by 

 what agency or means could so extensive, regular, 

 and conqjletc a chemical change have been made, as 

 converting all the shelly matter (carbonate of lime) 

 to gypsum, (sulphate of lime.) Secondly, admit- 

 ting the means toexist, and the change to have ta- 

 ken place, it is still more difficult to guess what 

 has become of the gypsum so formed — as not 

 one tenth of its proper quantity remains. When 

 sulphuric acid takes the place of carbonic acid, in 

 combination with lime, the greater weight of the 

 former, (together with the water chemically com- 

 bined) serves to increase the weight of the new 

 compound aViout fifty per cent : or, in other words, 

 one hundred grains of shells, or pure calcareous 

 earth, if allowed to combine with sulphuric acid, 

 will form at least one hundred and fifty grains of 

 gypsum. So the mere ciiange of acids being made, 

 ought to give us an earth much richer in gypsum 

 than it before was in calcareous matter. Instead 

 of this, the gypsum is no where so plenty as we 

 may suppose the shells formerly were ; and by 

 far the greater part of this bed now is entirely 

 destitute of both gypsum and calcareous earth. 

 What has become of it is beyond my power to 

 explain. 



The access of waters containing sulphuric acid, 

 or sulphate of iron, would suffice to produce the 

 change of carbonate to sulphate of lime — and the 

 exposure to sufficient water, and for sufficient 

 time, might dissolve and carry off the greater part 

 of the gypsum. Sulphate of iron is perceptible 

 on the surface of some of this earth near the head 

 of tidewater on Powell's creek, and was abundant 

 enough to greatly injure the land on v.'hich some of 

 that earth was applied thickly, for manure. Sul- 



