SOIL. 



The alumine and the oxyd of iron and manganefe, if they 

 exift, are all diflblved by the fulphuric acid ; they may 

 be feparated by carbonate of ammonia, wliich, added to 

 excefs, throws down the alumine, and leaves the oxyd of 

 iron in foliition, and this fubllance may be feparated from 

 the litjuor by boiling, by fuccinate of ammonia ufed to 

 excefs, which precipitates the oxyd of iron, and by foap- 

 ley, which diffolves the alumina, but not the oxyd of man- 

 ganefum : the weights of the oxyds afcertained after they 

 have been heated to rednefs, will denote their quantities. 

 Should any magnefia and lime have efcaped folution in the 

 muriatic acid, they vi'ill be found in the fulphuric acid ; this, 

 however, is fcarcely ever the cafe ; but the procefs for 

 detefting them, and afcertaining their quantities, is the 

 fame in both inftances. The method of analyfis by ful- 

 phuric acid, is fufRciently precife for all ufual experiments ; 

 but if very great accuracy be an objeft, dry carbonate of 

 potafh mull be employed as the agent, and the refiduum of 

 the incineration mull be heated red for half an hour, with 

 four times its weight of this fubllance, in a crucible of 

 iilvcr, or of well-baked porcelain. The mafs obtained mull 

 be diflblved in muriatic acid, and the folution evaporated 

 till it is nearly folid ; diftiUed water muft then be added, by 

 which the oxyd of iron and all the earths, except filex, 

 will be diflblved in combination as muriates. The filex, 

 after the ufual procefs of lixiviation, mull be heated red ; 

 the other fubltances may be feparated in the fame manner 

 as from the muriatic and fulphuric folutions. This procefs 

 is the one ufually employed by chemical philofophers for 

 the analyfis of Hones. 



10. Mode of dif covering foluble, animal, and vegetable 

 Matter, and/aline Matter. — If any faline matter, or foluble, 

 vegetable, or animal matter, is fufpefted in the foil, it will 

 be found in the water of lixiviation ufed for feparating the 

 fand. This water muft be evaporated to drynefs in an 

 appropriate dilh, at a heat below its boiling point. If 

 the folid matter obtained is of a brown colour, and in- 

 flammable, it may be confidered as partly vegetable ex- 

 traft. If its fmell, when expofed to heat, be ftrong and 

 fetid, like burnt feathers, it contains animal, mucilagi- 

 nous, or gelatinous fubftance ; if it be white and tranf- 

 parent, and not deftruftible by heat, it may be con- 

 fidered as principally fahne matter, the nature of which 

 may be known by the proper tefts. Nitrate of potalh 

 (nitre) or nitrate of lime, is indicated in this faline matter, 

 by its fcintillating with burning coal. Sulphate of mag- 

 nefia may be detefted by its bitter tafte ; and fulphate of 

 potafh produces no alteration in folution of carbonate of 

 ammonia, but precipitates folution of muriate of barytes. 



11. Mode of deteSing Sulphate of Lime (Gypfum) and 

 Phofphate of Lime in Soils. — Should fulphate or phofphate 

 of lime be fufpetled in the entire foil, the deteftion of them 

 requires a particular procefs upon it. A given weight of 

 it, 400 grains for inftance, muft be heated red for half an 

 hour in a crucible, mixed with one-third of powdered char- 

 coal. The mixture muft be boiled for a quarter of an hour, 

 in half a pint of water, and the fluid collefted through the 

 filter, and expofed for fome days to the atmofphere in an 

 open veil'el. If any foluble quantity of fulphate of lime 

 (gypfum) exifted in the foil, a white precipitate will gra- 

 dually form in the fluid, and the weiglit of it will indicate 

 the proportion. Phofphate of lime, if any exift, may be 

 feparated from the foil after the procefs for gypfum. Mu- 

 riatic acid mull be digefted upon the foil, in quantity more 

 than fufRcient to faturate the foluble earths, the folution muft 

 be evaporated, and water poured upon the fohd matter. 

 This fluid will diflblve the compounds of earths with the 



muriatic acid, and leave the phofphate of lime untouched. 

 It would not, the writer fays, fall within his hmits to detail 

 any procelfes for the detcilion of fubftances which may be 

 accidentally mixed with the matters of foils. Metallic 

 oxyds and earths of other kinds are, now and then, found in 

 them, but thefe in too minute quantities to bear any relation 

 to fertility or barrennefs, and the fearch for them would 

 make the analyfis much more complicated without rendering 

 it more ufeful. 



1 3. Statement of Refults and ProduSs. — When the examina- 

 tion of a foil is completed, the produdls fliould be clafled, 

 and their quantities added together ; and if they nearly 

 equal the original quantity of foil, the analyfis may be con- 

 fidered as accurate. It muft, however, be noticed, that 

 when phofphate or fulphate of lime are difcovered by the 

 independent procefs juft ftated, a correftion muft be made 

 for the general procefs, by fubtrafting a fum equal to their 

 weight from the quantity of carbonate of lime obtained 

 by precipitation from the muriatic acid. In arranging the 

 produds, the form fliould be in the order of the experiments 

 by which they were obtained. Thus, 400 grains of a good 

 filiceous fandy foil may be fuppofed to contain, and have 

 been aftually found to contain as follows : 



Grains. 

 Of water of abforption - - 18 to 19 



Of loofe ftones and gravel, principally filiceous, 42 53 

 Of undecompounded vegetable fibres - 10 14 



Of fine filiceous fand - - - 200 212 



270 298 



Of minutely divided matter feparated by filtration, and 

 confifting of 



Grains. 



Carbonate of lime - - - 19 to 25 



Carbonate of magnefia . - - 34 



Matter deftruftible by heat, principally vegetable, 15 10 



Silex - - - - - 2 1 40 



Alumine - - - - 1332 



Oxyd of iron - - - . 54 



Soluble matter, principally fulphate of potafli, 7 - 



common fait, and vegetable e.xtraft, - J 



Gypfum . . - . 23 



Phofphate of lime ... 02 



81 125 



298 270 



Amount of all the produfts in the different cafes 379 395 

 Lofs ----- 21 5 



In one of thefe inftances the lofs is fuppofed fmall ; but in 

 general, in aftual experiments, it will be found much greater, 

 as feen in the other, in confequence of the difficulty of col- 

 lefting the whole quantities of the different precipitates, and 

 the prefence of more moifture than is accounted for in the 

 water of abforption, and the lofs of it in the different pro- 

 ceffes. But when it is within thirty for four hundred grains, 

 there is no reafon to fufpeft any want of due precifion in the 

 procefles. 



13. This general Method of Analyfis may in many Cafes be 

 muchftmplified. — When the experimenter is become acquaint- 

 ed with the ufe of the different inftruments, the properties 

 of the re-agents, and the relation between the external and 

 chemical qualities of foils, he will feldom find it neceffary 

 to perform, in any one cafe, all the procefles that have been 

 defcribed. When his foil, for inftance, contains no notable 



proper- 



