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different plants, the latter has been found as yet only in the order of Compositæ, at least to any considerable extent.

Starch or inulin having been observed in the substance left after filtering and washing, this substance is tied up in gauze and kneaded. Collect the white powder deposited from the united liquid on a filter, dry at 110°, and weigh it. The liquid is thrown away, as the substance before kneaded had been exhausted already by cold water.

In order to find out the form and size of the starch or inulin obtained, they have to be examined under a microscope magnifying at least 400 diameters; after this, try their behaviour to warm water in order to determine their solubility or the temperature required for forming a paste. Any heterogeneous substance that has been kneaded out together with starch or inulin will remain on dissolving in water; as, for instance, oxalate of lime, which, on burning, yields carbonate of lime, the weight of which gives the weight of the oxalate of lime according to 625 (Ca O+CO 2) =1025 (Ca O + C2 O3 + 2HO). The weight of the oxalate of lime found in this way must be subtracted from that of the starch or inulin.

After the substance has been exhausted in the above manner by cold and lukewarm water, and eventually by kneading, determine its weight whilst still moist. Now take 5 grams of it, dry at 100°, weigh, calculate from it the weight of the whole residue, conceived dry, and subtract the latter weight from that of the substance, exhausted by ether and alcohol. The rest represents the weight of the substances including eventually starch or inulin; the weight of which, as found above, has to be subtracted from the rest in order to give the weight of the matters soluble in water. Heat the aqueous solution, obtained clear by filtering and subsiding, in a porcelain dish to the boiling-point; boil for about a quarter of an hour and allow to cool. Any turbidness or flocky precipitate is produced by albumin. Let subside, collect on a weighed filter, dry at 110°, and weigh. The albumin obtained is mostly of a dark colour, and, consequently, impure; but the colouring matter is hardly removable and is of too little amount to impair the numerical result.

Concentrate the filtered liquid to about 100 grams at a temperature not exceeding 70° to 80° (if, as usually, a little albumin should separate again, it must be collected and added to that obtained before); evaporate a small sample of it on a watch-glass to a thicker consistence, and allow both portions to stand cold, In case of crystals having formed in either of these liquids—a rare occurrence-evaporate the whole liquid to a small bulk, and keep in the cold. Collect what will have crystallised on a filter, wash with a little cold water, purify by recrystallising in hot water, and examine according to II., B, a or b or c.

The remaining liquid, mixed with the water that has been used for washing and evaporated again to the original weight of 100 grams, or the original aqueous solution reduced to the same weight after no crystals have been obtained from it-is examined in small quantities with the reagents indicated under II., B, d.

After these experiments have been made, precipitate and treat the remaining liquid as under II., B, e, f, g, successively with acetate of lead, ammonia and subacetate of lead, and examine the precipitates as indicated there.

The precipitate (e), obtained by acetate of lead, may in this case contain, besides the substances indicated there, gum and a protein-substance not identical with albumin. These substances will remain with the sulphide of lead as insoluble in alcohol. To ascertain their presence, wash the sulphide of lead well with alcohol, dry at 100°, triturate and shake with cold water. This dissolves the gum readily, and leaves behind the protein-substance rendered insoluble in water by drying and heating. The presence of gum in the cold water will be recognised by its forming on evaporation an amorphous tasteless varnish.

After this, digest the sulphide of lead with phosphoric acid of 1.04, warm, filter, edulcorate the remaining sulphide of lead with water, and neutralise the whole filtrate carefully by means of an alkali. The protein-substance is thrown down; collect it on a filter, wash, dry at 110°, and determine its weight. The quantity of the substance obtained hereby is insufficient for a closer investigation.

If no gum or protein-substance has been found in the leadprecipitate e, the lead-precipitates ƒ and g have to be tried for it, and this is done with the precipitate ƒ in the same manner as with precipitate e, whereas the precipitate g, its decomposition not being effected under alcohol but under water, is treated in the following way:-Boil the liquid, filtered off from the sulphide of lead and containing the gum, and probably the protein-substance, for a few minutes, when the protein-substance, if present, will separate; filter, evaporate to a small bulk, and shake a sample of the liquid with alcohol of 90%. If the mixture remains clear, no gum or protein-substance is present; if it becomes turbid, precipitate the whole liquid with alcohol, wash the sediment with alcohol, dry at 100°, and treat with cold water. A clear solution

contains only gum; any insoluble portion is protein-substance. As the sulphide of lead might in this case as well contain protein-substance, it must be treated as above, with phosphoric acid, &c.

The liquid, after separating from the precipitate, produced by lead-vinegar, is treated according to II., B, h.

V.-TREATMENT WITH BOILING WATER.

Mix the moist substance, exhausted by ether, alcohol and cold water, in a deep porcelain dish with so much water as to form a very thin pulp, heat under continual stirring to the boilingpoint, let boil for an hour, filter, or if necessary, strain through gauze in the manner indicated under IV., and wash the remnant with boiling water.

Determine the weight of the remaining substance in the supposed dry state according to IV., and subtract from the weight of the substance found under IV., the rest representing the weight of the matters dissolved in the boiling water.

Concentrate the united liquids to about 100 grams, and try in small portions with the tests indicated under II., B, d; in most cases slight or no reactions will be obtained.

If no inulin has been obtained under IV., examine on starch, by mixing a portion of the liquid with solution of iodine. A violet or blue colouration indicates starch, which is either a remnant from that obtained by kneading under IV., or it represents, if no starch has been obtained there, the whole amount of starch contained in the vegetable substance.

If no reaction of starch is obtained, a small amount of inulin might have been present in the vegetable substance, but is now converted into gum by the boiling water.

Any precipitate, produced by lead-salts, must be examined according to II., III. and IV.

VI. TREATMENT WITH DILUTED HYDROCHLORIC ACID. The substance exhausted by ether, alcohol and water, contains as a rule only constituents of minor interest, and in most cases the analysis may now be considered as finished. Considering, however, that the object of this work is to investigate every constituent of vegetables, though it be of minor interest, I now resort to those solving agents which, if employed in the beginning, would have caused alterations and decompositions highly detrimental to the analysis, but which now may be used with comparative impunity.

Give the substance left in V., and still moist, into a beaker (weighed before), make up with water to 500 grams, add 20 grams pure hydrochloric acid of 1.12 specific gravity, cover the beaker with a glass-plate and expose to a moderate heat for two days. Filter and wash the substance on a filter with water, until it passes off free from acid reaction.

After washing the substance, determine the weight of the dry substance as under IV., subtract from the weight under V. and note down the rest as the weight of the matters dissolved in the acid water.

(a) Saturate the acid extract, mixed with the water used for washing, with ammonia in excess. Generally only a darker colour is produced; should a turbidness be obtained, try, with a small quantity, if it becomes clear again by immediately over-saturating with acetic acid.* If this is not the case, oxalate of lime is present. Allow the liquid to become perfectly clear-sometimes (with barks, &c.) a jelly-like mass of pectic acid is obtained by over saturating with ammonia, which prevents the precipitate from subsiding, but may easily be dissolved in a gentle heat-collect the precipitate on a filter, wash with water and redissolve in dilute hydrochloric acid. Over-saturate the solution, if necessary after filtering, with ammonia and immediately afterwards with acetic acid, collect the deposit of pure oxalate of lime, dry at 100° and weigh it. This lime-compound contains, if no oxalic acid has been previously found, the whole of the oxalic acid contained in the original vegetable substance. In 100 parts of it = Ca O + C 03 + 2 HO are contained 43.90 parts oxalic acid. The oxalate of lime may also be converted into carbonate of lime by heating to a moderate red heat in an open crucible, and the oxalic acid may be calculated from the latter salt; 100 parts Ca O + CO 2 correspond to 72 parts oxalic acid.

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(b) Unite the liquid that has been separated from the precipitate effected by ammonia, with the liquid that has been separated from the pure oxalate of lime, over-saturate the mixture, if necessary, with ammonia, allow the precipitate to subside, collect on a filter, wash and dry. It consists chiefly of phosphate of lime and phosphate of ammonio-magnesia, but may eventually contain traces of alkaloïds, met with in the preceding sections, or possibly an alkaloïd that has not been affected by extracting with ether, alcohol and water. Submit it therefore to the influence of warm alcohol of 90%, filter and evaporate the filtrate. Any residue, obtained hereby, has to be examined according to II., B, a.

(c) Evaporate the liquid, left in b, to about 100 grams, in order to remove the excess of ammonia and of water, and try with a few sensitive alkaloïd tests which are without influence on ammonia-salts, viz., with tannic acid, chloride of gold, bi-iodide of potassium, iodide of potassio-mercury, iodide of potassio-bismuth, phosphate of soda, chloride of mercury, nitrate of palladium. In case of any turbidness, obtained, an alkaloïd may be present.

Usually, for economy's sake, tannic acid is employed for precipitating the whole liquid, if an alkaloïd is supposed to be present. Triturate the precipitate, obtained by tannic acid or by any other of the above tests, after washing and while still moist, intimately

*The acetic acid must be added immediately after the ammonia, because phosphate of lime and phosphate of ammonio-magnesia are only soluble in acetic acid when newly precipitated.

with an excess of burnt magnesia (or finely pulverised oxyd of lead or white of lead), dry in a gentle heat, pulverise, treat with cold water (in order to remove alkali-salts, chloride of magnesium, iodide of potassium, &c.), boil with alcohol of 90%, evaporate the alcoholic liquid and submit to examination what has remained.

(d) The remaining liquid may probably contain traces of dyeing matters, of gum and of resin, the further examination of which is perfectly valueless and involves only loss of time.

VII.-TREATMENT WITH DILUTED POTASH-LEY.

Bring the substance remaining after the treatment with hydrochloric acid, and while still in a moist state, back into the beaker, add water enough to make the whole up to 500 grams, dissolve in the mixture 10 grams hydrate of potash (or of soda), digest for two days in a temperature of 50° to 60°, let cool, filter and wash the residue thoroughly.

Dry 5 grams of the residue at 110°, weigh, calculate the weight of the whole residue conceived dry, and subtract this weight from the one obtained under VI., the rest representing the weight of the matters dissolved by the ley.

Should the mass prove too thick for filtering, it must be diluted previously, and is, if necessary, clarified by subsiding.

(a) The alkaline liquid is generally more or less brown, sometimes black-brown. By over-saturating with hydrochloric acid, a brown, flocky precipitate is invariably obtained, which contains so-called humic acids, but which may also contain protein-substances. The two substances are only incompletely separable by liquor of ammonia, the humic acids being more soluble in it than the protein-substances. For the quantitative estimation of the two bodies it is sufficient to collect the precipitate produced by hydrochloric acid, to wash, to dry at 120°, and to determine the amount of nitrogen by heating with soda-lime. By multiplying with 6 the weight of the nitrogen obtained, the quantity of the protein-substances is determined, and by subtracting the latter weight from that of the precipitate, the weight of the humic acids is obtained.

(b) The liquid obtained by filtering in a, contains small quantities of humic acids as well as of protein-substances, the closer investigation of which is impracticable.

(c) The residue left after the treatment with potash-ley, and the dry weight of which has been calculated, is generally accounted for as vegetable fibre or cellulose, though this name is not correct, as this fibre contains not only colouring matters but also mineral compounds. Regarding the complete removal of the first and the estimation of the latter impurities, see under Fibre, p.

82.

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