GYPSUM. 325 



the sulphate of lime decomposes this salt, carbonate of lime and 

 sulphate of ammonia being formed. I shall by and by inquire 

 whether the reaction that takes place is of the precise nature of that 

 here stated ; but admitting; for tiie present, that it is, it would still 

 be comprtent for us to ask if the quantity of ammonia condensed in 

 this way was likely to suffice for the production of such decided ef- 

 fects as we frequently witness in connection with the crops that are 

 assisted by gypsum. 



Professor Liebig observes that a pound of sulphate of lime once 

 converted into sulphate of ammonia, would introduce into the soil a 

 quantity of ammonia equivalent to that which would be afforded it 

 by 6.250 lbs. of horse's urine ; a showing upon which it would be 

 easy to demonstrate, taking the composition of sainfoin to be as I 

 have sho vn it, that a pound of plaster fertilizing the ground to this 

 extent, would be adequate to increase one hundred-fold the quantity 

 of dry fodder produced. 



According to my manner of viewing this question, it must be ex- 

 amined on a totally different basis. It is certain, for instance, that 

 gypsum has no effect upon natural meadows ; positive experience 

 has satisfied me of the absolute inutility of the substance here ; so 

 that upon my natural meadows at Bechelbronn, I now never employ 

 a particle of it. But let us review Professor Liebig's theory in con- 

 nection with the production of sainfoin and clover, which in a gene- 

 ral way derive an advantage from gypsum, which no one disputes. 



Our harvest of clover, taken as dry, amounts on an average from 

 strongly gypsed land, to 2 tons 1 cwt. very nearly per acre ; and 

 this quantity agrees pretty well with that which appears common in 

 Germany. It is generally allowed that by gypsing we double the 

 produce. It would follow from this, that an acre which had not 

 been gypsed, would yield no more than 20j cwts. of dry clover ; in 

 my opinion the reduction would be still greater. Dry clover hay, 

 made from the plant cut when in flower, contains about 2 per cent, 

 of azote. The 20| cwts. of forage gained by the intervention of the 

 gypsum would consequently contain 110 lbs. of ammonia, equivalent 

 to 134.2 lbs. carbonate of ammonia. This consequently is the quan- 

 tity of carbonate of ammonia which the gypsum ought to have been 

 the means of procuring from the rain which falls upon an acre of 

 land during the time that clover is upon the ground, in order to fur- 

 nish the azote contained in the increased quantity of the crop. 



Now in Alsace, from the time of gypsing in April, to the time of 

 mowing in July, there falls on an average 3.92, nearly 4 inches of 

 rain, which would amount in round numbers to 982 tons per acre. 

 Were the azote of what may be spoken of as the surplus produce, 

 derived from the rain in fact, all the water that falls ought to contain 

 TTm of its weight of carbonate of ammonia. It is very question- 

 able, however, whether any such proportion of ammoniacal salts 

 exist in rain-water ; yet the proportion ought to be very much great- 

 er, inasmuch as we have supposed the whole of the rain that fell to 

 penetrate the ground, none cf it to run off; but the truth is, that a 

 very considerable proportion of the rain that falls never sinks iato 



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