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Pepsin versus Animal Digestion. By E. F. LUDD (Amer. Chem. J., 8, 433-436; compare Abstr., 1886, 646).—It is shown that the artificial pepsin digestion yields results which are practically concordant with those obtained by animal digestion, as given in Kuhn's tables, &c. Armsby's statement that in a fodder over-rich in starch the digestibility of the albuminoïds is decreased, holds in the case of artificial pepsin digestion; and in a compound ration the results are not the same as with each separate component of the ration.

H. B. Formates in the Organism. By GREHANT and QUINQUAUD (Compt. rend., 104, 437-439).-Experiments with dogs show that when sodium formate is introduced into the blood or the digestive canal, the greater part is eliminated in the urine without undergoing any alteration. At the same time, the urine contains no excess of carbonates.

The organic liquid was acidified with sulphuric acid and distilled in a vacuum on a water-bath. The distillate was neutralised, evaporated to a small bulk, and the formate thus obtained was decomposed with strong sulphuric acid, and the volume of evolved carbonic oxide measured. Experiments with an aqueous solution of the formate, and with urine to which a known quantity of formate had been added, gave the necessary correction. C. H. B.

Reducing Substance in Diabetic Urine. By H. LEO (Chem. Centr., 1887, 193-194).-In addition to dextrose, the author has isolated from diabetic urine a reducing substance which, after being purified from dextrose by repeated treatment with barium hydroxide in methylic alcohol solution, is obtained as a bright-yellow syrup. Its aqueous solution has a strong left-handed rotation, [a] being -26-07°; it is not fermented by yeast, even after being boiled with hydrochloric acid, and it has the composition CH12O6. reducing power is very much less than that of dextrose. The author suggests that this substance can be determined in diabetic urine by taking the reducing power and optical activity of the urine, removing the dextrose by fermentation, and again determining these constants. G. H. M.

Its

Creatinine in Urine. By P. GROCCO (Chem. Centr., 1887, 1718). The author has modified Neubauer's method for the determination of creatinine as follows: During the 24 hours' collection of the sample the urine must be kept acid, if necessary, by the addition of acetic acid, and if possible must be immersed in ice, otherwise a little creatinine may be converted into creatine. An excess of acid is removed by the addition of milk of lime. The urine is then neutralised with lime, calcium chloride added, and the mixture evaporated; the reaction should be either neutral or feebly acid. If the acidity is due to a mineral acid, great care is necessary, and it is advisable to add sodium acetate to the alcoholic extract of the syrupy residue in order to replace it by acetic acid. It is better, however, to entirely dispense with the use of mineral acid and use only acetic acid. The alcoholic solution, to which zinc chloride is to be added, must contain free acetic acid, in order to prevent the precipitation of zinc oxide. Oń

the other hand too much acetic acid prevents the precipitation of the creatinine zinc chloride. If necessary, the alcoholic extract should be decolorised with animal charcoal before acidification. It is better to cool the solution with ice before adding the zinc chloride. The precipitated creatinine zinc chloride should always be submitted to a microscopic examination with a high power.

With the aid of this method, the author has determined the amount of creatinine in normal and pathological urine. In childhood and old age, human urine contains less creatinine than in middle age. In infants fed with an entire milk diet it does not always occur, but, contrary to Hofmann's statement, it is sometimes found in small quantities during the first months of life. The amount of creatinine increases with a diet of animal food, and decreases on fasting or with a vegetable diet. With increased bodily work, the author found, contrary to Hofmann, that the secretion of creatinine through the kidneys is increased. For the influence of various diseases on the secretion of creatinine in the urine, the original must be consulted.

G. H. M.

Behaviour of Quinol with Urine and Urea. By A. N. ANRAEFF (Vrach, 1887, 230-232).-The author finds that quinol prevents the alkaline fermentation of urine, an addition of 2 per cent. keeping urine without apparent change either to the eye or to testpaper for 25 days. 1 per cent. prevented it from becoming acid or giving off an ammoniacal odour, the reaction being neutral.

Quinol decomposes urea, the solution becoming more and more tawny in colour; the amount of decomposition produced by quinol is proportional to the quantity of urea present. Thus solutions of urea containing 1, 2, and 3 per cent. of urea showed a loss respectively of 1, 0.5, and 0.2 per cent. of the urea present when kept for 24 hours without admixture; solutions of like strength to which 1 per cent. of quinol had been added, showed losses of 17, 19, 15, and 13.25 per cent. of the urea present. It is suggested that quinol acts like acids on urea, decomposing it into ammonia and carbonic anhydride, but at the same time forming a new combination with the former, which is not readily decomposed by sodium hypobromite. This theory would account for the deficiency of nitrogen always observed when solutions of urea containing quinol are analysed.

Quinol was found in the urine by Mering after the administration of arbutin (Archiv. f. die gesammte Physiol., 1877, 62, 276), and after taking phenol by Baumann and Preusse (Abstr., 1879, 814).

T. M.

Aniline Poisoning. By F. MÜLLER (Chem. Centr., 1887, 193).— Unchanged aniliue was found in the urine of a person poisoned with aniline; the urine reduced Fehling's solution, but did not rotate polarised light. Free sulphuric acid was present in small quantity (4.75 mgrms. in 100 c.c.), and combined sulphuric acid in large quantity (761 mgrms. in 100 c.c.). A portion of the concentrated urine, when boiled with strong hydrochloric acid, neutralised with sodium hydroxide and extracted with ether, gave an ethereal extract which, when tested, showed the blue indophenol reaction. The ethereal

extract of the unboiled urine did not give this reaction; therefore the aniline must have been secreted as paramidophenyl sulphate. The striking resemblance which patients who have been treated with antifebrin show to persons poisoned with aniline led the author to examine the urine in each case. In both cases methæmoglobin is found in the blood. Aniline does not occur in the urine of patients treated with antifebrin, but by the above treatment it shows the indophenol reaction. Combined sulphuric acid is also present. The

author therefore concludes that antifebrin is secreted in the urine in the same form as aniline, that is, as paramidophenyl sulphate. This can be tested for by boiling a little urine with one-fourth its volume of strong hydrochloric acid, adding a few c.c. of a 3 per cent. phenol solution, and then some drops of a chromic acid solution. If paramidophenol is present, the liquid becomes red and changes to blue on addition of ammonia. G. H. M.

Toxic Action of Colchicine. By A. MAIRET and COMBEMALE (Comp. rend., 104, 439-441).-Experiments with dogs and cats show that colchicine behaves as an irritant poison and attacks all the organs, but especially the digestive canal and the kidneys. The action is more rapid when the drug is injected hypodermically than when it is introduced into the stomach. In the first case the minimum fatal dose is 0.000571 gram per kilo. of body-weight; in the second case, 0.00125 per kilo. Details of the symptoms are given in the original paper.

Colchicine is eliminated by various secretions and chiefly in the urine, but the elimination is very slow, and therefore colchicine may behave as a cumulative poison if administered in minute quantities at not too great intervals. C. H. B.

Chemistry of Vegetable Physiology and Agriculture.

Liberation of Nitrogen from its Compounds, and the Acquisition of Atmospheric Nitrogen by Plants. By W. O. ATWATER (Amer. Chem. J., 8, 398–420; compare Abstr., 1885, 1005, and this vol., p. 292). The conclusions arrived at are (1.) During the growth of peas, nitrogen is in most cases acquired from the air, but in some few cases where the conditions of growth are abnormal, there is either no gain in nitrogen or there is a slight loss. This loss is to be explained by the evolution of free nitrogen from the nutriment, or from the seeds and plants during germination and growth; it is probably a constant, and may cause considerable error in all the experiments. (2.) Boussingault has found the amount of atmospheric nitrogen absorbed to be very small, but in his experiments the plants were not normally nourished, and probably, therefore, were less able to resist the action of denitrifying ferments, or to absorb nitrogen from the air. (3.) Numerous experiments have shown a slight gain

or loss of nitrogen during germination and growth, but the failure of an experiment to show the acquisition of nitrogen from the air proves the non-assimilation of atmospheric nitrogen only on condition of the further proof that no nitrogen was liberated, whilst a gain actually observed is positive proof that nitrogen is assimilated either directly by the plants or indirectly through the medium in which the roots developed. (4.) The liberation of nitrogen appears to be due, in some cases, if not in all, to ferments, and it is to be noticed that in nearly all the experiments in which no gain of nitrogen has been observed the plants have been ill fed, or the nutritive solutions have been very concentrated, or other conditions have been abnormal. (5.) The way in which the nitrogen is acquired is still a matter of doubt. (6.) The experiments of Boussingault, and of Lawes, Gilbert, and Pugh which have given the strongest evidence against the fixation of free nitrogen by plants are possibly affected by the loss of nitrogen already referred to, by the exclusion of the action of electricity and of microbes, and by the fact that the plants were also for the most part poorly fed. (7.) In the author's experiments, ignited sea-sand was used for growing the plants in, and hence it is probable that the plants themselves and not the soil are factors in the acquisition of atmospheric nitrogen. (8.) Lawes, Gilbert, and Warington have shown the great probability that the legumes, which appear to possess in high degree the power of obtaining nitrogen from natural sources, induce the action of nitrifying ferments by which the inert nitrogen of the soil is made available. It is equally conceivable that the same plants and others may favour the action of nitrogen-fixing_microorganisms. H. B.

The Functions of Chlorophyll. By A. NAGAMATSZ (Chem. Centr., 1887, 163-164).-The behaviour of leaves, when immersed in an aqueous solution of carbonic anhydride, depends on whether the water thoroughly wets them, or whether they remain covered by a thin film of air. In the former case no starch is formed, in the latter a great deal.

The slight thickness of the chlorophyll-bearing layer in leaves and other assimilating organs, coupled with the fact that light which has been filtered through a chlorophyll solution possesses in a very slight degree only the power of causing the leaves of aquatic plants to separate oxygen, makes it probable that light, which has passed through an assimilating leaf, no longer possesses the power of causing assimilation in a second leaf. Direct experiments showed that sunlight which had passed through a layer of chlorophyll-containing tissue less than 0.2 mm. thick, was completely deprived of the power of causing assimilation. Etiolated leaves do not possess the power of producing starch.

G. H. M.

By A. VOGEL (Bied.

Influence of Ozone on Germination. Centr., 1887, 142).-Strongly ozonised air seems to have no harmful influence on the germination of seeds. Milk and meat can be kept for a longer time in ozonized air, without change, than in ordinary air. E. W. P.

Formation of Sugar in Grapes. By MÜLLER (Ann. Agronom., 13, 88-91; from Bot. Centralbl., 27, 116).-The author gives a résumé of some of the principal results of researches on this subject which have been published at the various Conferences of Viticulturists since 1876. The sugar in the grape is a transformation product of starch formed in the leaves, and the green grape itself takes little or no part in its formation; individual grapes of a cluster ripen normally when protected from the light. Assimilation in the grape itself is never active enough to mask respiration. The starch formed in the leaves exposed to light disappears completely when they are placed in darkness for two days. Again placed in the light a new formation of starch can be detected after three-quarters of an hour. 100 grams of leaves (Risling) destroy by respiration alone 3-4 grams sugar in 24 hours. The migration of the reserve materials depends essentially on the temperature; the higher this is the more rapidly do they find their way through the tissues and towards the fruit, the action being most rapid at 30°. The diminution of acidity is not explained by neutralisation of the acid, but by the relation of acid production to respiration. The more energetic the oxidation of the sugar, the more acid will be formed; the acid already formed is further oxidised, ultimately to carbonic anhydride and water. In the ripe grape, the intensity of metamorphosis and the production of acid diminish together.

To ensure the maximum production of sugar, as many leaves as possible must be left on the vine; there is no practical limit to this except the shade produced by too many leaves. The following table shows the effect of leaving 2, 4, 6, or all the leaves on the twig below each bunch of grapes :

:

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There is thus less sugar and more acid when the leaves are removed. The grapes are less mature, and less lævulose is formed:

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Presence of Cinnamic Acid in Plants of the Ericaceæ Family. By F. J. EIJKMAN (Rec. Trav. Chim., 5. 297–298). From the leaves of the Enkianthus Japonicus, an ornamental plant in Japanese gardens, the author has extracted by means of chloroform a crystalline sub

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