466 



THE FARMERS' REGISTER. 



not the smallest portion of the ammonia is lost to the 

 plants, it is all dissolved by water, and imbibed by 

 their roots."— (pp. 140, 141, 142.) 



The next passage, immediately succeeding, is a 

 most interesting and valuable application ol the 

 action of chemical affinities to the preservation of 

 ammonia and fixing it in tlie soil, for the future 

 use ol plants, by means ofcypsum. But we deem 

 the explanation thenoe deduced, ol'the modus ope- 

 randi ofgypsum as manure, as entirely unsupport- 

 ed by experiment, or even by plausibility. 



"The evident influence ofgypsum upon the o-rowth 

 of grasses, — the strikinf; fertility and luxuriance of 

 a meadow upon which it is strewed, — depends only 

 upon its fixinsiin the soil the ammonia of the atmo- 

 sphere, which would otherwise be volatilized, with the 

 water which evaporates. The carbonate of ammonia 

 contained in rain water is decomposed by gypsum, 

 in precisel)' the same manner as in the manufacture 

 of sal-ammoniac. Soluble sulphate of ammonia and 

 carbonate of lime are formed ; and this salt of ammo- 

 nia possessing no volatility is consequently retained 

 in the soil. AH the gypsum gradually disappears, but 

 its action upon the carbonate of ammonia continues 

 as long as a trace of it exists. 



" The benficial influence of gypsum and of many 

 other salts has been compared to that of aromatics, 

 which increase the activity of the human stomach 

 and intestines, and give a tone to the whole system. 

 But plants contain no nerves; we know of no sub- 

 stance capable of exciting them to intoxication and 

 madness, or of lulling them to sleep and repose. No 

 substance can possibly cause their leaves to appro- 

 priate a greater quantity of carbon from the atmo- 

 sphere, when the other constituents v.hich the seeds, 

 roots, and leaves require for their growth are wantiijg. 

 The favorable action of small quantities of aromatics 

 upon man, when mixed with his food, is undeniable, 

 but aromatics are given to plants toithoiit food to be 

 digested, and still they flourish with greater luxuriance. 



•' It is quite evident, therefore, that the common view 

 concerning the influence of certain salts upon the 

 growth of plants evinces only ignorance of its cause. 



"The action of gypsum or chloride of calcium 

 (bleaching sal's) really consists in their giving a fixed 

 condition to the nitrogen, — or ammonia which is 

 brought into the soil, and which is indispensable for 

 the nutrition of plants. 



" In order to form a conception of the effect of gyp- 

 sura, it maybe sufficient to remark that 100 Hess. lbs. 

 of burned gypsum fixes as much ammonia in the soil 

 as 6250 lbs. of horse's urine would yield to it, even 

 on the supposition that all the nitrogen of the urea 

 and hippuric acid were absorbed by the plants without 

 the smallest loss, in the form of carbonate of ammonia. 

 If we admit with Boussingault, that the nitrogen in 

 grass amounts to 1-100 of its weight, then every 

 pound of nitrogen which we add increases the produce 

 of the meadow 100 lbs., and this increased produce of 

 100 lbs. is effected by the aid of a little more than 

 four pounds of gypsum. 



" Water is absolutely necessary to effect the decompo- 

 sition of the gypsum, on account of its difiicult solu- 

 bility, (1 part of gypsum requires 400 parts of water 

 for solution,) and also to assist in the absorption of 

 the sulphate of ammonia by the plants; hence it 

 happens that the influence of gypsum is not observable 

 on diy fields and meadows. 



" The decomposition of gypsum by carbonate of am- 

 monia does not take place instantaneously ; on the con- 

 trary, it proceeds very gradually, and this explains 

 why the action of the gypsum lasts for several years. " 

 --(pp. 142, 143, 144.) 



These facts should teach the farmer the im- 

 mense importance of saving, by immediately 

 mixing and combining with gypsum, all the urine 



of man and beast that is usually almost entirely 

 wasted ; and which in towns lorms u nuisance la 

 its waste, and would be a commercial commodity 

 ol great leriilizing value, and ai the same time be 

 kept free liom all oiiensiveness, li so treated. 

 This pan ol the instruction cannot be loo strongly 

 mipressed on country agriculturists, and upon 

 town guardians ol healui and police. But we 

 utterly deny that the mysterious action ofgypsum 

 as manure iu hereby accounted lor ; though this 

 view oi Lieiug's has been readily received by 

 other revievveis in this country, and set Ibrih as 

 entirely saiislaciory. Our objections cannot be 

 here presented at length, auu will be merely an- 

 nounced as concisely as possible. 



In the first place, in all the vaiious attempts 

 made by theorisis and by chemists to explain the 

 modus operundi of gypsum as manure, not one 

 has been scUislaclory, or has served to meet all the 

 common and well known cases of opposiie re- 

 sults. Davy's opinion, to lar as ii goes, seems 

 the most sound, and the only one thai does not 

 lead manilestly to error, lie su|)poses thai gyp- 

 sum IS a necessary though always a very small 

 ingredient ol cerlain plants, as clover, and there- 

 lore 11 musi be a specific manure lor such plants, 

 unless gypsum be already present in the soil ; and 

 if so present, in the very small quantity required, 

 that more gypsum ajiplied as manure would be 

 superfiuous, and of no efieci. We lake this opi- 

 nion 10 be sound and true. But ii does not explain 

 what almosi every iheorizer on the subject has al- 

 lempied lo explain, ichy and how gypsum is a ma- 

 nure at all, and still less thai il should have such 

 woiiderlul efi-cis when lully operative. 



ill another place, we have iorraeriy endeavored 

 to show, not indeed why or how gyjjsum acts as a 

 manure, but vvliy u does not and cannot act on the 

 many soils where it is always lound lo be inopera- 

 tive. Our view was, thai the gypsum was speed- 

 ily decunqjosed by the acid ol .lie soil, and a new 

 salt of lime lormed, which might be, and proba- 

 bly was, usetui as manure to some extent ; but it 

 was no longer gypsum — and ol course could not 

 exhibit the peculiar and vvonderlul productive 

 power which gypsum alone, of all mineral ma- 

 nures, has shown in such very light dressings as 

 a bushel to the acre. 



Now, as complete a decomposition, and change 

 of |)riiiciples, is supposed by Liebig, in ihe double 

 decom|)osition and re-composition of the elementa 

 of the two substances of which he treats. The 

 separate salts, sulphate of lime (gypsum) and 

 carbonate of ammonia, exchange principles, and 

 become two other separate salts, carbonate of 

 lime and sulphate of ammonia. And in the lat- 

 ter, ihe ammonia being fixed instead of volatile, 

 (as in carbonate of ammonia,) it is to this quality 

 of being fixed that Liebig ascribes all the benefits 

 produced by the application of gypsum. It is not 

 gypsum, according lo his view, which acts, but am- 

 monia j and thai, not by being supplied anew, or 

 in addition, but merely by being made more fixed 

 and permanent in the soil. 



We have no doubt but thai the sulphate of am- 

 monia, as ol every salt of ammonia, must be va- 

 luable manure. Bui before claiming lor it all the 

 wonders produced by gypsum, it would have con- 

 formed more to inductive science, and would have 



* Essay on Calcareous Manures, 2d ed., pp. 57, 92. 



