ANALYSIS. 



dered as soluble humus, and the immediate 

 fertility of the soil depends greatly on the 

 quantity of it. 



To recapitulate what has been obtained, 

 we shall have the coarse grit in sieve No. 1 ; 

 the sand in Nos. 2 and 3; the fine earth 

 separated in the tubes, Nos. 1 and 3 ; the 

 humus in tube No. 2, and on the filtering 

 paper, and on the soluble parts in the evapo- 

 rating dish. All these substances must be 

 well dri'-d over the fire, as was done with the 

 soil at first, and each separated part accurate- 

 /hed: the sum of them ought to be 

 equal to tin- original portion of soil subjected 

 to analysis after the water was drawn off; but 

 there always is a loss, even with the most ex- 

 perienced "analyser; this loss will be princi- 

 pally in the finer parts which are dissipated in 

 the operation. But the analysis is not yet 

 completed: we have separated" the sand, clay, 

 and humus, but there may be a portion of car- 

 .i'liine in tin- f'-rni -f s;.nd, or of finely 

 divided earth mixed with the other earths. To 

 ascertain thi . rtioa, excepting the Ira- 



put into a separate nip, and a little 

 muriatic acid, diluted with f..ur times its ( ,\vn 

 ured on it : if there is 



any effervescence, it shows the presence of 

 carbonate of lime; diluted acid is then added 

 gradually, u < is re- 



newed by the addition. When this < 

 and tli' water continues to have an acid taste, 

 more pure v Mrd, and each portion 



separately filtered, dried, and weighed. The 

 it in each of these gives the quan- 

 ','onate of lime dissolved by the 

 muriatic acid, and which has passed with the 

 water in the form of muriate of lime. Th- 

 weights being now collected, the re- 

 sult of the operations may be set down. There 

 may be many mineral substances in the soil, 

 which this mode of analysing will not detect; 

 and s,,me of these may materially n fleet the 

 fertility. In most cases there will be some- 

 thing to indicate the presence of metals. Iron 

 abounds in most soils: when the quantity is 

 considerable, it will be detected by pouring a 

 decoction of gall-nuts into the water which 

 has washed the earth; it will immediately be- 

 come of a bluish dark colour. The other me- 

 tals are not of frequent occurrence. Sulphate 

 of lime or gypsum, and also magnesia, are 

 found in some soils; but the separation of 

 them can only be effected by those who are 

 well acquainted with chemistry: they fortu- 

 nately occur very seldom, and the places 

 where they are found are generally well 

 known. For all practical purposes it is suf- 

 ficient to ascertain the proportion of sand, 

 clays, carbonate of lime, and humus, which 

 any soil contains. Many soils which have 

 been highly manured, contain portions of un- 

 decomposed vegetable substances, and fibres 

 of roots : these will be found mixed with the 

 coarser earths separated by the sifting: not 

 bein^ a part of the natural soil, they need not 

 be taken into the account ; but they may be 

 separated by washing the earths, as they are 

 much lighter, and will come over in the first 

 decantations. They may be dned and weighed, 



is 



ANALYSIS. 



and the quantity set down in the result, if it ig 

 desirable. Some very barren sands, contain- 

 ing very little argillaceous earth or humus, 

 may readily be known by the copious sandy 

 deposit which they rapidly make when dif- 

 fused through water. Good natural loams are 

 not so easily judged of; but the preceding 

 mode of analysis will in general detect their 

 intrinsic value. When a soil contains peaty 

 matter, it is easily discovered by the irregular 

 black particles which are visible in it. Peat 

 differs from humus only in being in a different 

 state of decomposition, and containing a con- 

 siderable portion of tannin : when acted upon 

 by lime or alkalies, and brought into a state 

 of greater decomposition, it is not to be dis- 

 tinguished from humus in its qualities. The 

 only instruments absolutely required for the 

 foregoing analysis are, in the first place, twc 

 good balances, one capable of weighing a 

 pound and turning with a grain, and one 

 weighing two ounces and turning with the 

 tenth part of a grain. Next, the combination 

 of sieves which we have described, and which 

 may easily be made by any tinsmith. But any 

 sieves of the required fineness, whether of 

 metal, horse-hair, or silk, provided they be of 

 the proper texture, will answer the purpose 

 for a trial. Some earthen or glass jugs, and 

 two or three glass tubes, 18 inches long, open 

 at both ends, which may be obtained at any 

 glass-blower's or chemist's, a glass funnel, 

 and some filtering paper, will complete the 

 apparatus. The only chemical substance in- 

 dispensable to the analysis is some muriatic 

 acid, commonly called spirit of salt. A little 

 test-paper to detect acids in the water with 

 which the soil has been washed, and an infu- 

 sion of gall-nuts to ascertain the presence of 

 iron, may be useful. A small glass phial will 

 serve for the specific gravities. The whole 

 of these instruments and materials may be 

 procured for a very small sum. If the fore- 

 going process is carefully followed, any per- 

 son, however unaccustomed to chemical ope- 

 rations, will soon be enabled to satisfy him- 

 self as to the composition of any soil of which 

 he desires to know the comparative value. He 

 must not be disheartened by a few failures at 

 first. However simple every operation may 

 appear, it requires a little practice and much 

 patience, if we would come to a very accurate 

 result. Every portion must be dried to the 

 same degree before it is weighed : minute por- 

 tions which adhere to the vessels when dried 

 must be carefully collected by scraping and 

 brushing off with a feather : pieces of filtering- 

 paper and linen must be weighed before they 

 are used, that small portions of matter adher- 

 ing to them may be ascertained by the in- 

 crease of weight. By attending to these par- 

 ticulars, it is surprising how nearly the whole 

 original weight is accounted for in the sum- 

 ming up of the separate parts. If this mecha- 

 nical analysis should be thought lightly of by 

 experienced chemists, let them only carefully 

 analyse a portion of soil by this process, and 

 then another by any more perfect mode, and 

 compare the importance of the results as re- 

 gards practical agriculture. The object is to 

 H 2 8* 



