99.74 per cent. of glycerides. The lead salt was used to cause separation of the liquid and solid fatty acids, when it was found that of the latter there was 6:55 per cent. and of the former 93:45 per cent. present.

The quantitative reactions are given in the original.

When grown as a field crop, Lallemantia yielded 2031 kilos. seed and 6314 kilos. straw per hectare. E. W. P.

Are Nitrates indispensable for the Growth of Field Crops ? By O. PITSCH (Landw. Versuchs-Stat., 34, 217-258).—The carefully conducted experiments for the elucidation of the above question appear to be most satisfactory, and the decision arrived at is that at any rate barley, oats, beans, and wheat can and do grow in a soil absolutely destitute of nitrates, free from all nitrifying bacteria, but in which nitrogenous manures are present as ammonium sulphate. The experiments were made during two seasons, and all the precautions taken, the progress of the various plants grown, and the apparatus employed are fully detailed. In outline, a rich soil was first heated in an oil-bath to destroy all bacteria, then thoroughly washed by upward displacement, to free it from all nitrates, again heated and then placed, the first year, in large beaker glasses, and in the second season in iron vessels 62 cm. x 25 cm.; the seeds were sown, and a thick covering of cotton wool placed on the surface of the soil in a suitable holder of wire net, so as to prevent access of all aerial spores; distilled water was used for watering by a special method described in full, whereby the water was admitted from below. Two sets of such vessels and

seeds were employed. To the soils used in the first year, bicalcium potassium phosphates and ammonium sulphate were added, both to the original and to the parallel sets, the difference between the two being that the soil of the parallel sets was neither heated nor covered over with cotton wool. In the second year, however, the soil underwent the same process in both sets, but in place of ammonium sulphate being added to the controlling sets, sodium nitrate was added, and no cotton wool used. The results in both years were, however, similar, namely, that the growth of the plants under such peculiar conditions as total absence of nitrates was not largely affected-certainly there was a difference, but not at all remarkable; the plants were able to grow healthily, but perhaps not robustly without any nitrates. It was noticed that those plants which could obtain no nitrates, but had to be content with nitrogen in other forms, came to a standstill for a short time early in their growth, and after a short period of rest, again grew normally. The author tried to account for this in the first year, by the fact that as the manure had not been mixed thoroughly with the soil throughout its whole depth, the lower roots were unable to obtain nitrogen, consequently no growth was made until new roots were formed higher up, but after the experiments of the second season had been made, he was obliged to abandon this theory, for although he had mixed the manure thoroughly with the soil, yet this arrest of growth again occurred, whilst no such effect was produced in the soil containing nitrates. E. W. P.

Agricultural Experiments. By J. RAULIN (Compt. rend., 105, 411-414). In order to avoid, in agricultural experiments, errors due to differences between the natural fertility of contiguous patches of soil, the experimental plot should be divided into three rectangular sections, A, B, and C, which are treated separately. As a rule, the results with A and C differ, and in a few cases the differences are quite irregular. Usually, however, the fertility of the plot varies gradually, so that the mean of A and C is practically identical with B. Experiments made in this way show that superphosphates and precipitated calcium phosphate produce a distinct increase in the wheat crop, whilst with fossil phosphates and with slags the results are doubtful, the apparent increase not being greater than the variations between the three sections of the plot. C. H. B.

Analytical Chemistry.

Grinding Mill for Minerals. By K.. ZULKOWSKY (Ber., 20, 2664-2669).-A. description of a mill in which minerals may be readily reduced to fine powder. The grinding surfaces are of agate, and the pestle is so arranged that it can be rotated by a water-motor against the lower surface with a pressure capable of being varied at will. The material, already reduced to the coarseness of sand, is introduced into the mill through a sector cut in the pestle..

W. P. W.

Determination of Sulphur in Pyrites. By J. W. WESTMORELAND (J. Soc. Chem. Ind., 6, 84-87).-It is shown that the results obtained by Lunge's "old process" (precipitation of the sulphur from ferric solutions), agree closely with those given by the new process (precipitation after separation of the ferric oxide by ammonia), which is therefore a needless elaboration. The new method is also liable to losses caused by an extra filtration and washing, and by sulphur retained in the ferric oxide, whilst sulphur is liable to be introduced by the ammonia and hydrochloric acid employed. The results obtained by Lunge's processes express the total percentage of sulphur in Spanish pyrites; it is, however, necessary to use only a moderate excess of barium chloride for precipitation, great care being taken in the use of hydrochloric acid when washing this precipitate.

D. B.

Estimation of Sulphur in Pyrites. By G. LUNGE (J. Soc. Chem. Ind., 6, 96). The author criticises Welch's process (Abstr., 1887, 180) for assaying iron pyrites for sulphur available for sulphuric acid manufacture, and shows that the experiments having been made with impure lead sulphide are not conclusive. D.. B.

Kjeldahl's Method of Estimating Nitrogen. By F. W. DAFERT (Landw. Versuchs-Stat., 34, 311-353).-In this article, are detailed

in full the results of experiments made for the purpose of testing the value of Kjeldahl's process for estimating organic nitrogen, and of an examination of the various modifications of this process, as recommended by Kreusler and others.

Estimation by the Original Process.-Certain nitrogenous compounds only seem to yield their nitrogen in the ammoniacal forms, the result being that the process is inaccurate with regard to others; of the latter class, anilines and hydrazines are special examples, but some compounds, contrary to expectation, yield their nitrogen as ammonia more readily than others; as for instance, it was expected that hydrazines would yield ammonia more completely and quickly than nitrocompounds, but the contrary is the case.

The Action of the Sulphuric Acid. To aid the solution of this question, Kreusler's modification, where phosphoric anhydride is added to the sulphuric acid, was employed; sugar was also added. The explanation which is given is, that the sulphuric acid removes from the substance the elements of water and of ammonia, and the sulphurous anhydride formed in the reaction reduces the nitrogenous compound; the addition of organic matter (sugar) to the nitrogenous compound slackens the formation of ammonia when the compound is not volatilised by the acid; consequently to obtain quantitative results, the sulphuric acid must not volatilise the compound, nor completely decompose it, for the analysis of some substances by this method free nitrogen accompanies the ammonia.

The Action of Permanganate.-The presence of the permanganate when used in company with the mixture of acids, causes a destruction of the organic matter present, the nitrogen being so separated that nearly the whole of it is transformed into ammonia; as a rule this modification of Kjeldahl's process may be employed for all quantitative analyses, but it is necessary that the mixture shall be thoroughly and sufficiently heated.

The Addition of Metallic Salts.-This modification of Wilfarth's renders the original process more rapid, although the time required for the analysis is shortened very considerably by the addition of mercury, it is at the cost of accuracy; it should only be introduced in those cases where very stable compounds are under examination, or also when the compounds readily give up their nitrogen as ammonia. From careful examination, it appears that the discrepancies which exist between the results obtained by Kjeldahl's original method, Wilfarth's and Ulsch's (addition of platinum chloride), are due to loss of nitrogen as nitrogen, and not to an insufficiency of heating, when the compound is only slightly stable. The author considers that Wilfarth's explanation of the reaction which occurs when metallic salts are present, is satisfactory, but he also adds that when those compounds which do not resist the action of sulphuric acid well, or which are readily oxidised, are dealt with, the addition of the metallic salt causing violent oxidation, ammonia may be in part replaced by nitrogen; increasing the quantity of platinum, addition of oxygen and mixing with organic substances may also result in loss, even when the compound is not easily decomposed. Mercury should be always employed when very stable compounds are to be analysed; amines

and alkaloïds resist oxidation, but Ulsch's process must not be used because of its uncertainty, except in special cases, for example, with potassium nitrate.

General Application.-Nitrogenous compounds may be divided into two classes as regards the applicability to them of Kjeldahl's process of analysis. In the first are placed those which can be analysed without any previous treatment, for example, all amides and ammonium bases, pyrroline and quinoline compounds, alkaloids, bitter substances, albuminoïds and their allies, and perhaps the indole group; whilst to the second class belong all nitro-, nitroso-, azo-, diazo-, hydrazo-, and azoamido-compounds, nitrates and nitrites, the hydrazines, and possibly the cyano-compounds. Two methods may be employed for the previous treatment of this second class: addition of an organic substance, or reduction with zinc-dust, and even the two combined, but the choice of which is to be used must rest with the analyst. This uncertainty will for the present preclude Kjeldahl's process, or its improvements, from supplanting Dumas's older and exact method. For the estimation of nitro-compounds, it is recommended to dissolve the substance in 10 c.c. of alcohol (or if it is very stable, directly in sulphuric acid) decompose by zinc-dust, add 10 c.c. of acid, and warm until all alcohol is got rid of; when this is accomplished, add 10 c.c. of the acid mixture together with mercury, and then proceed as with an ordinary compound. When distilling with sodium hydroxide, special care must be taken to avoid shaking the flask; it is therefore advisable to apply heat by means of a sand-bath; in the same manner nitroso- and azo-compounds may be readily analysed. Hydrazo-compounds must first be converted into azo-compounds, before exposing them to the action of the sulphuric acid. The author, for example, heats the sulphate of phenylhydrazine first with excess of cane-sugar in presence of sodium acetate for some hours on a waterbath; after drying the resulting mass, the acid may be added. Most cyano-compounds, as far as the author is aware, can be analysed by this process, but some may exist which will not bear the method.

E. W. P.

Notes on Nesslerising. By J. M. MILNE (J. Soc. Chem. Ind., 6, 33). The author recommends Hehner's method in which the nesslerising is conducted in graduated cylinders having a somewhat broad foot, a glass tap being fused into their sides near the bottom, so that the solution, either standard or water distillate, may be run out until the two tints correspond. This method, a description of which was given in Chem. News, 33, 185, is very simple and readily carried out. As nesslerising cannot be done in gaslight, the author proposes to imitate the process with two shades of indigo solution. D. B.

Estimation of Ammonia in Soils by the Knop-Wolf Method. By A. BAUMANN (Landw. Versuchs-Stat., 34, 259-276).-A reply to Knop (ibid., 33, 438).

Moisture and Free Acid in Superphosphates and similar Fertilisers. By J. RUFFLE (J. Soc. Chem. Ind., 6, 327-333).-It is

shown that the soluble phosphoric acid existing in superphosphates is not entirely present as monocalcium phosphate, and that exposure to 100° drives off more than the true moisture, that is, the adhering uncombined water. It is recommended to determine the moisture in the following manner:-Weigh out 2 to 5 grams of the superphosphate in its natural state on a double watch-glass, place under an air-pump over dry calcium chloride, exhaust, then leave for 18 to 24 hours and weigh. The author shows that the acidity of ordinary superphosphates and ammoniated superphosphates is due to phosphoric acid, and not to sulphuric acid. In ammoniated superphosphates, monocalcium phosphate is substantially absent, the free acid being phosphoric acid. D. B.

Detection of Small Amounts of Carbonic Anhydride and other Gases. By O. RÖSSLER (Ber., 20, 2629-2631).—A small test-tube is drawn out at the lower end to a capillary; this is bent upwards, and cut off at a distance of 1 cm. from the bend. A capillary funnel is then made of such a size that the upper end fits the test-tube, the lower end being at a distance of 15 to 2 cm. from the bottom. The substance to be tested for carbonic anhydride is put into the outer tube, the capillary funnel containing baryta-water fitted, and the lower end of the apparatus then dipped into hydrochloric acid. With 0.0005 gram of sodium carbonate a very distinct turbidity, with 0.00005 gram a distinct turbidity is produced in the drop of baryta-water at the end of the capillary. It is possible to detect 0.02 milligram of carbonic anhydride. Sulphuric and nitric acids, hydrogen sulphide, ammonia, &c., can also be detected by means of the apparatus, using iodide of starch, ferrous chloride, lead acetate, and copper sulphate respectively. A sketch of the apparatus is given. N. H. M.

Absorption of Carbonic Oxide by Cuprous Chloride. By H. DREHSCHMIDT (Ber., 20, 2752-2755).-Hempel has recently shown. that in certain cases when cuprous chloride is used as an absorbent of carbonic oxide in gas analysis, there is an increase instead of a decrease of volume. This result is explained on the supposition that the ethylene contained in the absorption-liquid is driven out by the absorbed carbonic oxide. It is here shown that this explanation is not sufficiently valid, as similar results were obtained with mixtures of carbonic oxide, with hydrogen, or nitrogen only. Experiments are described in which a given volume of hydrogen was added to the volume of gas obtained after some of the carbonic oxide had been absorbed; on completing the absorption, a fresh quantity of carbonic oxide was added, and the experiment repeated. In all cases, whether an ammoniacal or hydrochloric acid solution of cuprous chloride was used, an increase of volume of the hydrogen was observed, the increment being greater in the case of the acid solution. It is advisable, therefore, when carbonic oxide is present in small quantities, to use a fresh ammoniacal solution, or to burn with air by means of palladium asbestos. If the amount of carbonic oxide is large, a portion of the gas is unabsorbed, and must subsequently be determined by the above methods. V. H. V.