treat the residue with some chlorine water (to remove the of confirmation, convert the lithia found into phosphate 3. If you have not yet clearly detected ammonia in 1 (249), add 260 to a large quantity of the water hydrochloric acid to acid reaction, and concentrate the fluid considerably by boiling in a retort. Add now, through the tubular neck of the retort, an excess of milk of lime, made with recently calcined hydrate of lime, boil, and conduct the vapor into a flask containing very dilute hydrochloric acid, which is kept cool by surrounding it with ice or with very cold water; evaporate the contents almost to dryness, and then test for ammonia with hydrate of lime or with bichloride of platinum. 2. EXAMINATION OF THE SINTER-DEPOSIT. § 212. 1. Free the ochreous or sinter-deposit from impurities, by picking, 261 sifting, elutriation, &c., and from the soluble salts adhering to it, by washing with water; digest a large quantity (about 200 grammes) of the residue with water and hydrochloric acid (effervescence: CARBONIC ACID) until the soluble part is completely dissolved; dilute, cool, filter, and wash the residue. a. Examination of the filtrate. a. Saturate the larger portion of the filtrate nearly with 262 carbonate of soda, add a few drops of dilute sulphuric acid, and let the mixture stand for 24 hours at a gentle heat. If a precipitate is found to have formed after this time, filter, wash the precipitate, pour hydrosulphuric acid over it, that you may not overlook the possible presence of sulphate of lead, and test for BARYTA and STRONTIA as directed § 211, 2, c, a, aa (255). Boil the fluid filtered from this precipitate with sulphite of soda-if necessary, with addition of some hydrochloric acid, as the fluid must always remain acid-to reduce the sesquioxide of iron to protoxide, and the arsenic acid, which may be present, to arsenious acid; heat finally, until all sulphurous acid is expelled, and conduct for some hours a slow stream of washed hydrosulphuric acid gas into the fluid; let the latter now stand in a moderately warm place, until the smell of hydrosulphuric acid has become quite faint. If a precipitate has formed, 263 The precipitate designated in § 92 as phosphate of soda and lithia, is 3 Li 0, P 0. (Mayer, "Annal. d. Chem. u. Pharm.," 98, 193). filter, wash, and digest with dilute solution of soda and some sulphide of sodium; filter, and mix the filtrate with hydrochloric acid to acid reaction. If a precipitate is produced, test, a. A portion of it for ARSENIC, with cyanide of potassium and carbonate of soda in a stream of carbonic acid. b. Treat the remainder as directed § 190, that traces of ANTIMONY and TIN, which may be present, may not be overlooked. If a residue has been left upon treating the precipitate 264 produced by hydrosulphuric acid with solution of soda and sulphide of sodium, boil it, together with the filter, with a very little dilute nitric acid, filter, wash, and examine the contents of the filter, as directed in § 212, a, a (262), for sulphate of lead, sulphate of baryta, and sulphate of strontia (the two latter salts are more soluble in solution of sesquichloride of iron than in solution of protochloride of iron. Mix the filtrate (the nitric acid solution) with some pure sulphuric acid, evaporate on the water-bath to dryness, and treat the residue with water. If this leaves an undissolved residue, the latter consists of sulphate of LEAD. To make quite sure, filter, wash the residue, treat it with hydrosulphuric acid water, and observe whether that reagent imparts a black color to it. Test the fluid filtered from the sulphate of lead which may have separated, a with ammonia, b with ferrocyanide of potassium, for COPPER. Of the fluid filtered from the precipitate produced by 265 hydrosulphuric acid, examine in the first place, after having expelled the hydrosulphuric acid by boiling, a portion with molybdate of ammonia for PHOSPHORIC ACID; mix the remainder in a flask with chloride of ammonium, ammonia, and yellowish sulphide of ammonium, close the flask, and let it stand in a moderately warm place until the fluid above the precipitate looks no longer greenish, but yellow; filter, and wash the precipitate with water to which some sulphide of ammonium has been added. Dissolve the washed precipitate in hydrochloric acid, separate the SILICIC ACID by evaporation, moisten the residue with hydrochloric acid, add water, warm, and test the solution for ALUMINA, IRON, MANGANESE, and ZINC, according to the directions of § 192, 1. Examine now the fluid filtered from the precipitate produced by sulphide of ammonium, for LIME and MAGNESIA in the usual way. 6. Mix a portion of the hydrochloric acid solution with chloride of barium, and let the mixture stand 12 hours in a warm place. The formation of a white precipitate indicates the presence of SULPHURIC ACID. b. Examination of the residue. This consists usually of silicic acid, clay, and organic mat- 266 ters, but it may also contain sulphate of baryta and sulphate of strontia. Boil in the first place with solution of soda or potassa, to dissolve the SILICIC ACID; then fuse the residue with carbonate of soda and potassa, and a little nitrate of potassa. Boil the mass, wash the residue, and then dissolve it in some hydrochloric acid; boil the solution, add ammonia, filter the fluid from the ALUMINA, &c., which may precipitate, evaporate the filtrate to dryness, gently ignite the residue, redissolve it in very little water, with addition of a drop of hydrochloric acid, and test for BARYTA and STRONTIA as directed $211, 2, c, a, aa (255). 2. As regards the examination for FLUORINE, the best way is to 267 take for this purpose a separate portion of the ochreous or sinterdeposit. Ignite (which operation will also reveal the presence of organic matters), stir with water, add acetic acid to acid reaction, evaporate until the acetic acid is completely expelled, and proceed as described in § 211, 2, b (252). 3. Boil the ochreous or sinter-deposit for a considerable time with 268 concentrated solution of potassa or soda, and filter. a. Acidify a portion of the filtrate with acetic acid, add ammonia, let the mixture stand 12 hours, and then filter the fluid from the precipitate of alumina and hydrated silicic acid, which usually forms; again add acetic acid to acid reaction, and then a solution of neutral acetate of copper. If a brownish precipitate is formed, this consists of APOCRENATE of copper. Mix the fluid filtered from the precipitate with carbonate of ammonia, until the green color has changed to blue, and warm. If a bluish-green precipitate is produced, this consists of CRENATE of copper. b. If you have detected arsenic, use the remainder of the alkaline fluid to ascertain whether the arsenic existed in the sinter as arsenious acid or as arsenic acid. Compare § 133, 6. IV. ANALYSIS OF SOILS. § 213. Soils must necessarily contain all the constituents which are found in the plants growing upon them, with the exception of those supplied by the atmosphere and the rain. When we find, therefore, a plant the constituent elements of which are known, growing in a certain soil, the mere fact of its growing there gives us some insight into the composition of that soil, and may accordingly save us, to some extent, the trouble of a qualitative analysis. Viewed in this light, it would appear quite superfluous to make a qualitative analysis of soils still capable of producing plants; for it is well known that the ashes of plants contain almost invariably the same constituents, and the differences between them are caused principally by differences in the relative proportions in which the several constituents are present. But if, in the qualitative analysis of a soil, regard is had also-in so far as may be done by a simple estimation to the quantities and proportions of the several constituent ingredients, and to the state and condition in which they are found to be present in the soil, an analysis of the kind, if combined with an examination of the physical properties of the soil, and a mechanical separation of its component parts,* may give most useful results, enabling the analyst to judge sufficiently of the condition of the soil, to supersede the necessity of a quantitative analysis, which would require much time, and is a far more difficult task. As plants can only absorb substances in a state of solution, it is a matter of especial importance, in the qualitative analysis of a soil, to know which are the constituents that are soluble in water; which those that require an acid for their solution (in nature principally carbonic acid); and, finally, which those that are neither soluble in water nor in acids, and are not, accordingly, in a position for the time being to afford nutriment to the plant. With regard to the insoluble substances, another interesting question to answer is, whether they suffer disintegration readily, or slowly and with difficulty, or whether they altogether resist the action of disintegrating agencies; and also what are the products which they yield upon their disintegration.† In the analysis of soils, the constituents soluble in water, those soluble in acids, and the insoluble constituents must be examined separately. The examination of the organic portion also demands a separate process. The analysis is therefore properly divided into the following four parts: 1. Preparation and Examination of the Aqueous Extract. § 214. About two pounds (1000 grammes) of the air-dried soil are used 269 for the preparation of the aqueous extract. To prepare this extract quite clear is a matter of some difficulty; in following the usual course, viz., digesting or boiling the earth with water, and then filtering, the fine particles of clay are speedily found to impede the operation, by choking up the pores of the filter; they also almost invariably render the filtrate turbid, at least the portion which passes through first. I have found the following method the most practical. Close the neck of several middle-sized funnels with small filters of coarse blotting paper, moisten the paper, press it close to the sides of the funnels, and then introduce the air-dried soil, in small lumps ranging from the size of a pea to that of a walnut, but not pulverized or even crushed; fill the funnels with the soil to the extent of about two-thirds. Pour distilled water into them, in sufficient quantity to cover the soil; if the first portion of the filtrate is turbid, pour it back on the filter. Let the operation proceed quietly. When the first quantity of the fluid has passed, fill the *With regard to the mechanical separation of the component parts of a soil, and the examination of its physical properties and chemical condition, compare Fr. Schulze's paper "Anleitung zur Untersuchung der Ackererden auf ihre wichtigsten physikalischen Eigenschaften und Bestandtheile."-Journal f. prakt. Chemie, Vol. 47, p. 241, For more ample information on this subject I refer the reader to Fresenius' "Chemie für Landwirthe, Forstmänner und Cameralisten ;" published at Brunswick, by F. Vieweg and Son, 1847, p. 485. Recommended by Fr. Schulze "Anleitung zur Untersuchung der Ackererden auf ihre wichtigsten physikalischen Eigenschaften und Bestandtheile."-Journ. f. prakt. Chemie, Vol. 47, p. 241. funnels a second, and after this a third time. Collect the several filtrates in one vessel. Treat the contents of one of the funnels repeatedly with hot water, in order to remove the soluble matter as far as practicable, the lixiviated soil being required for the preparation of the acid extract. a. Concentrate two-thirds of the aqueous solution by cau- 270 tiously evaporating in a porcelain dish, filter off a portion, and test its reaction; put aside a portion of the filtrate for the subsequent examination for organic matters, according to the directions of 4. Warm the remainder, and add nitric acid. Evolution of gas indicates the presence of an ALKALINE CARBONATE. Then test with nitrate of silver for CHLORINE. b. Transfer the remainder of the concentrated fluid, together with the precipitate which usually forms in the process of concentration, to a small porcelain, or, which is preferable, a small platinum dish, evaporate to dryness, and cautiously heat the brownish residue over the lamp until complete destruction of the organic matter is effected. In presence of NITRATES this operation is attended with deflagration, which is more or less violent according to the greater or smaller proportion in which these salts are present. c. Test a small portion of the gently ignited residue with carbonate of soda before the blowpipe for MANGANESE. d. Warm the remainder with water, add some hydrochloric acid (effervescence indicates the presence of CARBONIC ACID), evaporate to dryness, heat a little more strongly, to effect the complete separation of the silicic acid, moisten with hydrochloric acid, add water, warm, and filter. The washed residue generally contains some carbon, and also a little clayif the aqueous extract was not perfectly clear-and lastly SILICIC ACID. To detect the latter, make a hole in the point of the filter, rinse the residue through, boil with solution of carbonate of soda, filter, saturate with hydrochloric acid, evaporate to dryness, and treat the residue with water, which will leave the silicic acid undissolved. e. Test a small portion of the hydrochloric acid solution 271 with chloride of barium for SULPHURIC ACID; another portion with molybdate of ammonia for PHOSPHORIC ACID; a third portion with sulphocyanide of potassium for SESQUIOXIDE OF IRON. Add to the remainder a few drops of sesquichloride of iron (to remove the phosphoric acid), then ammonia cautiously until the fluid is slightly alkaline, warm a little, filter, throw down the LIME from the filtrate by means of oxalate of ammonia, and proceed for the detection of MAGNESIA, potassa, and SODA, in the usual way, strictly according to the directions of $194. f. Alumina is not likely to be found in the aqueous extract. 272 (Fr. Schulze never found any). However, if you wish to test for it, boil the ammonia precipitate obtained in e (271) with pure solution of soda or potassa, filter, and test the filtrate with chloride of ammonium. g. If you have detected iron, test a portion of the remaining 273 third of the aqueous extract with ferricyanide of potassium, another with sulphocyanide of potassium, both after previous |