On August 2nd, the plant had begun to flower, and on September 30th it had begun to die.

From these results it follows that manures containing phosphorus and nitrogen are of no value after the plant has begun to flower, but manures containing potassium may be useful throughout the whole period of growth. C. H. B.

Acidity of Cell Sap. By LANGE (Ann. Agronom., 14, 134–135, from Bot. Centr., 32, 236).—The author finds that acidification of the cell-sap during the night, and the disappearance of acid during the day, are changes not special to one or two groups of plants, but common to plants of all classes. The diurnal de-acidification is more energetic in the red half of the spectrum than in the blue. In this the author's results agree with those of Kraus and Warburg, and are opposed to those of de Vries. J. M. H. M.

Saccharine Matter in Peach-gum. By R. W. BAUER (Landw. Versuchs-Stat., 1888, 33-34).-Peach-gum was boiled with 5 per cent. sulphuric acid for four hours, then neutralised with chalk, the filtrate after evaporation to a syrup extracted with alcohol, and the filtrate evaporated over sulphuric acid. The syrup remained unaltered some months, but after the introduction of a small quantity of pure dextrose, galactose, and arabinose, a mass of crystals was formed. After purification, these crystals seemed to be identical with galactose from agar-agar.

E. W. P.

Injury to Plants by Kiln Smoke. By E. W. PREVOST (Landw. Versuchs-Stat., 1888, 25-28).—The results obtained corroborate the observations of Schroeder (Bied. Centr., 1884, 535) and Reuss, as regards the damage effected by smoke from furnaces; in this special case, the fumes came from brick-works, and the leaves of the various plants (rhubarb, pear, pine, larch trees, &c.), all showed brown spots on them, and in the case of the pines and larches the ends of the needles were affected; analyses show an increase of sulphuric acid in the leaf. The author is of opinion that leaves may be in an unhealthy state without any visible signs, these signs only appearing at a later date; he draws this conclusion from the fact that some samples which were collected and appeared to be healthy, showed minute spots on them after having been removed from the deleterious atmosphere for 12 hours. E. W. P.

Percentage of Sulphuric Acid in Plants Damaged by Sulphurous Anhydride. By E. MACH (Landw. Versuchs-Stat., 1888, 52-53).—Hay made from grass which had been damaged by fumes from a cellulose factory in the Tyrol was submitted to analysis; the results showed that the percentage of water was much reduced, from 13.65 to 7:55 per cent., the pure ash was reduced from 9.77 to 8:36, whilst the sulphuric acid was raised in the dry matter from 0.54 to 0.818 and 0.96, and in the pure ash from 6:35 to 8-64 and 11.59. E. W. P.

Titanic Oxide in Soils. By G. F. McCALEB (Amer. Chem. J., 10, 36-37).-Using Weller's hydrogen peroxide colorimetric test (Abstr., 1883, 381), a number of samples of soil from Virginia, U.S., have been examined, and all found to contain titanic oxide in quantities varying from 0·3 to 2.8, and even 5'4 per cent. H. B.

Sources of the Nitrogen of Vegetation. By J. B. LAWES and J. H. GILBERT (Proc. Roy. Soc., 43, 108-116).-Land which had been exhausted of nitrogen by successive crops of beans, gave a very large crop when sown with barley and clover. Numerous experiments were made to determine the source of the nitrogen. As the surface soil was richer in nitrogen after the crop had been grown, the nitrogen could not have been derived from that source. The clay subsoil was found to be susceptible to nitrification, especially in the presence of Leguminosa, but the necessary secretion was a difficulty. In order to see if the acidity of the sap could account for the nitrogen obtained, soils were treated with organic acids. The amount of nitrogen obtained in this way was small, and less after long than after short contact. The nitrogen so taken up seems to exist in the soil in the form of amides, and the question arises whether the plant takes up the amide as such or converts it into ammonia and nitric acid. To test this, urea, uric acid, hippuric acid, quinine, ammonium phosphate, glycocine, creatine, and tyrosine were used in the water-culture method and in soil. Nitrogen was undoubtedly taken up, but in the soil experiments the organic compound appeared to have been decomposed; urea appears to be taken up as such. The evidence as to whether nitrogen is taken up from the air is very conflicting. The absorption, if any, has been attributed to electrical action, or to the agency of micro-organisms. In any case, the amount taken up would not suffice for the compensation usually supposed to take place. H. K. T.

Conversion of Nitrates in Soils into Nitrogenous Organic Compounds. By BERTHELOT (Compt. rend., 106, 638-641).— 43.3 kilos. of moist earth, containing 723 grams or 1.669 grams per kilo. of organic nitrogen, was mixed with 361.5 grams of potassium nitrate, and a quantity of water sufficient to produce a 4 per cent. solution of the nitrate. The earth was then exposed to the air for six months, care being taken to protect it from rain. At the end of this time, the amount of organic nitrogen had increased by 164 grams or 0.3777 gram per kilo., a quantity equal to about one-fourth of the

original organic nitrogen, and about one-third of the nitrogen in the potassium nitrate.

A similar quantity of earth with the same quantity of alkaline nitrate was planted with 11 roots of Amarantus pyramidalis, weighing 1-899 grams. After growth, the total weight of the dried plants was 197-2 grams, and they contained 5.83 grams of nitrogen. The quan tity of organic nitrogen in the soil was practically the same as at the end of the first experiment, and was equal to about one-third of the nitrogen in the nitrate. The quantity of nitrogen and of nitrates in the plant was much below that found in former experiments, notwithstanding the large proportion of nitrate in the soil. It follows that the formation of nitrates in Amarantus is a complex process.

The assimilation by plants of the nitrogen existing in soils as nitrates is preceded or accompanied by a conversion of the nitrogen of the nitrates into nitrogenous organic compounds in the soil, either by the action of microbes or by pure chemical processes.

In all soils the formation of nitrates by the action of aerobic microbes is opposed by the action of the anaerobic microbes, which produce fermentative and putrefactive changes and thus tend to reduce the nitrogen to nitrogenous compounds, or even to cause its liberation in the free state. The antagonism between these two classes of orga nisms explains the fact that nitrification reaches a limit before the whole of the nitrogen present is converted into nitrates. C. H. B.

Absorption of Nitrogen by Soils and Plants. By A. GAUTIER and R. DROUIN (Compt. rend., 106, 754-757, 863-866, and 944-947). An artificial soil (A) was prepared by mixing 60 parts of Fontainebleau sand, washed with strong acids and then with water, and containing 0.5 per cent. of gelatinous silica, with 30 parts of pure precipitated calcium carbonate, 10 parts of pure washed kaolin, and 3 parts of neutral potassium phosphate. A second soil (B) was prepared by mixing A with 5 per cent. of ferric oxide; a third (C) by mixing 1100 25 grams of A with 22.5 grams powdered wood charcoal, washed with acids, and 2:25 grams of ulmic acid from sugar and hydrochloric acid; and a fourth (D) by mixing 10627 grams of A with 37.5 grams of ferric oxide, 22.5 grams of charcoal, and 2.25 grams of ulmic acid.

Quantities of the soils, with or without vegetation, were exposed to the air in pots in such a manner that they were completely permeable by the air, but were protected from rain. The total nitrogen was determined by a modification of Dumas' process, and the ammonia and nitrates by Schloesing's method. The quantity of soil used in each experiment was about 1200 grams.

A first series of observations was made with the four soils in which no plants were growing, the exposure to air extending from August 14th to October 31st, 1887, the soil being watered from time to time. With A, the total nitrogen diminished from 0·1181 to 0.1137 in one case and 0.1054 in another, the losses being respectively 0.0044 and 0·0127; with B, it diminished from 0·1252 to 0·0987 in one case and 0·1106 in another, the losses being 0·0294 and 0.0175 respectively.

When the soil contained organic matter, however, the results were different. With C, the nitrogen increased from 0·2344 to 0·3349, or a gain of 01005; with D, it increased from 0.2437 to 0.2592 in one case and 04451 in the other, the gain being 00155 and 0·2014 respectively. The small increase in the first case is due to the fact that the earth had settled in the pot, and was much less permeable to the air. The same soils were sown with broad beans, which assimilate considerable quantities of nitrogen and are regarded by agriculturists as constituting a crop which enriches the soil in this element. The following results were obtained, the beans being sown on August 14th, and the plants cut down at the end of October :

Total nitrogen.

:

Nitrogen in the soil.

Increase.

These results show that soil free from organic matter loses part of its nitrogen when exposed to the air, but if it contains organic matter it is able to absorb nitrogen from the air independently of vegetation. When, however, the soil is supporting vegetation, a still greater quantity of nitrogen is absorbed by those which contained organic matter, and a considerable quantity is absorbed by soils. which previously contained no organic matter, and hence of themselves absorbed no nitrogen.

C. H. B.

Relation between Atmospheric Nitrogen and Vegetable Soils. By T. SCHLOESING (Compt. rend., 106, 805-809, and 898902).—It has already been shown that nitrogen, like oxygen, cannot undergo any physical condensation in the pores of ordinary vegetable soil. If nitrogen is absorbed from the atmosphere, it must be fixed. chemically or otherwise by the organic matter, since none of the inorganic constituents of the soil absorb nitrogen. Boussingault found that when air and soil were allowed to remain in contact for 11 years in hermetically sealed flasks, there was no increase in the quantity of nitrogen in the soil, but some of the nitrogenous organic matter was converted into nitrates at the expense of the oxygen of the air. In consequence of the direct contradiction between these results and those recently obtained by Berthelot and André, the author has repeated Boussingault's experiments with certain modifications.

The soil was enclosed in flasks with long necks, which were rendered vacuous, and pure air of known composition was allowed to enter. The necks were then bent over, and the open ends placed under mercury. The neck of each flask contained a quantity of

calcium oxide, which absorbed the carbonic anhydride produced by the oxidation of the organic matter in the soil, and the absorption of oxygen was indicated by the rise of the mercury in the neck. Pure oxygen was introduced from time to time in order to maintain an excess of this gas in the atmosphere in the flask. After a sufficient length of time, the air remaining in the flask was analysed. By operating in this manner the accurate methods of eudiometry are substituted for the much less accurate plan of determining the amount of nitrogen in the soil. Complete details of the experiments are given in the second paper. Six soils of different character were employed. In each case, there was a large absorption of oxygen, with evolution of carbonic anhydride, the combustion of the organic matter in the soil proceeding to an extent varying with the nature of the soil. During this combustion, nitrates are formed, and the ammonia in the soil disappears. The variations in the volume of the nitrogen in the globes are not greater than the errors of experiment; the greatest variation actually observed corresponds with the absorption of 16 kilos. of nitrogen in 14 months by 4000 tonnes of soil, arranged in a layer 03 metre deep. C. H. B.

Mealy and Steely Barley. By W. JOHANNSEN (Landw. VersuchsStat., 1888, 19-23).-After several samples of barley had been moistened with an equal quantity of water, and then dried, it was found that the mealiness of the grain was dependent on the percentage of nitrogen, thus grains containing less than 1:41 per cent. N showed a degree of mealiness denoted by 95, whereas those containing 2.00 per cent. were classed as 30. Experiments further showed that if steely barley is slightly moistened and then dried, it will yield as good a malt as if it had been more mealy. E. W. P.

Sugars and Starch in Fodders and their Determination. By E. F. LADD (Amer. Chem. J., 10, 49–53).—With wheat and its products, freshly prepared diastase gives an amount of starch (as determined by Fehling's solution) comparing favourably with that obtained by inversion with acid; but diastase hardly acts on the starch contents of hay and similar products. As regards the inversion by acids, it was found that with starch rather higher results were obtained by the use of sulphuric acid, but with hays and fodders more uniform and slightly higher figures were obtained by the use of hydrochloric acid. The amount of hydrochloric acid necessary is 3 to 5 c.c. for 5 grams fodder, or 3 grams starch and 150 c.c. of water; the action is complete in 11 hours. A number of analyses are given, showing the percentages of saccharose, glucose, starch, nitrogen-free extract and starch in various corns and fodders; the influence of the time of cutting and the action of various fertilisers are also briefly referred to. H. B.

Farmyard Manure. By P. P. DEHÉRAIN (Ann. Agronom., 14, 97133). As to the result of a survey of his own work and that of others, the author concludes that litter impregnated with the solid