December, 1913. 



KNOWLEDGE. 



463 



with the Chemistry Section, which was opened by Professor 

 Moore with an account of various methods of bringing about 

 the synthesis of formaldehyde from carbon dioxide and water 

 by inorganic colloids acting as transformers of light energy ; 

 and by a paper in which Mr. W. N. Jones described some 

 recent investigations in pigment (anthocyan) formation. 



Ecology was represented by three papers on maritime 

 vegetation. Professor Oliver dealt with the distribution of 

 Suaeda fruticosa and its role in the stabilising of shingle, 

 pointing out that while all shingle plants to some extent 

 modify or retard the landward movement to which shingle 

 beaches are liable, when very high tides are accompanied by 

 onshore gales, Suaeda fruticosa, from its shrubby habit of 

 growth and high capacity of rejuvenescence, is the most 

 effective stabiliser of all British shingle plants. Miss W. H. 

 Wortham described some features of the sand dunes in the 

 south-western corner of Anglesey, with special reference to 

 the succession of the various plant associations ; while Mr. 

 P. H. Allen gave a preliminary account of the observations 

 made by a party from the Cambridge University Botany 

 School on the maritime plant associations at Holme, Norfolk, 

 the chief feature of the area being a sandy salt marsh, though 

 there are also sand dunes and shingle banks. 



CHEMISTRY. 



By C. Ainsworth Mitchell, B.A. (Oxon.), F.I.C. 



ACTION OF ALKALINE WATER ON LEAD.— The 

 water consumed in Birmingham, which is mainly derived from 

 Wales, is slightly alkaline, and unless subjected to special 

 treatment has a pronounced action upon bright sheet lead. 

 To obviate risk of danger from this cause a small amount of 

 powdered chalk is added to the water in the Welsh reservoirs. 

 The results of experiments upon this solvent action of the 

 water are described by Messrs. Liverseege and Knapp in a 

 communication to the British Association. 



In these experiments, which were continued over a period 

 of five years, it was found that different portions of a lead 

 pipe behaved differently in this respect, and that the resistance 

 offered to the water increased with the lapse of time. New 

 lead pipes were rendered more resistant to the action of 

 the water by treatment with a dilute solution of potassium 

 permanganate. The erosion of sheet lead by the water 

 depended upon the simultaneous action of oxygen, and its 

 degree varied with the distance of the metal from the surface. 



Carbon dioxide had but little effect in preventing the action 

 of the water unless present in a quantity exceeding two per 

 cent, by volume. Under those conditions the erosion of the 

 lead was stopped, but the metal was dissolved in appreciable 

 quantities. An addition of lime in proportions within the 

 limits of three to nine parts per one hundred thousand 

 reduced the erosive action, but larger or smaller quantities 

 had little, if any, effect. The best results were obtained by 

 treating the water with not less than four parts of calcium 

 carbonate or not less than two parts of calcium bicarbonate 

 per one hundred thousand. 



THE FIXATION OF NITROGEN BY FELSPAR.— A 

 mode of decomposing felspar, and its use in the fixation of 

 atmospheric nitrogen, is described by Mr. W. H. Ross in the 

 Journ. Ind. Eng. Chem. (1913, V, 725). If a current of 

 nitrogen be passed over a mixture of felspar and carbon 

 which has been heated to a temperature of 1400° C. only a 

 small proportion of the nitrogen is retained by the ignited 

 mass, but by adding calcium carbonate or lime to the mixture 

 a relatively large amount becomes fixed. In the reaction that 

 takes place the potassium of the felspar is liberated and 

 volatilised, and more nitrogen is fixed than would be required 

 to form a nitride of aluminium. For example, a mixture of 

 two parts of felspar, two parts of carbon, and 4-3 parts of 

 calcium carbonate when ignited at 1400° C. in a current of 

 nitrogen fixed 6-1 per cent, of nitrogen in one hour and 7*4 

 per cent, in two hours. The fixed nitrogen may be very 

 slowly liberated in the form of ammonia by boiling the 

 product of the reaction with water or with a solution of 

 sodium hydroxide. 



THE FORMATION OF ALKALOIDS IN PLANTS.— 

 From the results of experiments upon Datura and tobacco 

 plants Messrs. Ciamician and Ravenna (Chem. Zeit., 1913, 

 XXXVII, 1156) have drawn the conclusion that vegetable 

 alkaloids may be formed from amino-acids. For example, green 

 tobacco plants normally contain about 0-15 per cent, of 

 nicotine, but by inoculating them with various organic 

 compounds the proportion of alkaloid could be more than 

 doubled. Thus, after treatment of the plant with pyridine 

 tartrate, the amount of nicotine was raised to 0-22 per cent., 

 while with asparagin it was increased to 0-25 per cent., and 

 with benzoic acid and quinol up to 0-4 per cent. Dextrose 

 also led to an increased production of nicotine, whereas 

 phthalic acid caused the proportion to be less than normal. 

 Analogous results were obtained by treating Datura plants 

 with pyridine, piperidine and carbopyrrolic acids, the first of 

 these compounds causing the greatest increase in the alkaloidal 

 production. In the case of both plants there was complete 

 assimilation of the added substances. 



ABSORPTION OF OXYGEN BY COAL.— An investiga- 

 tion that has an important bearing upon the spontaneous 

 ignition of coal has been made by Mr. T. F. Winmill (Times, 

 Eng. Suppl., Oct. 1st, 1913). In each series of experiments 

 coal-dust from coal taken from different parts of the Barnsley 

 seam was exposed to the air at a temperature of 30° C. and the 

 rate of oxidation determined. It was found that during the 

 first hour or two the rate of absorption of oxygen was very 

 rapid, and that the quantity absorbed was approximately 

 proportional to the nature and amount of the carbonaceous 

 matter present. As much as a tenth of a cubic centimetre of 

 oxygen was absorbed by one hundred grammes of the coal 

 dust during this initial oxidation, which lasted about forty-eight 

 hours. The speed of absorption then became much slower, 

 but it was possible for the increase of temperature produced 

 during the first stage of oxidation to accelerate the velocity of 

 this second stage to such an extent that, given favourable 

 conditions, there was risk of ignition taking place. The 

 reduction of the proportion of oxygen in the air did not 

 prevent the initial oxidation, while the use of coarser coal- 

 dust having only one four- hundredth of the surface of the fine 

 dust only reduced the speed of oxidation by 28 per cent. A 

 rapid increase in the velocity of the absorption followed each 

 increase of the temperature. 



MICRO-ORGANISMS PRODUCING ARSINE— The 

 conditions under which it is possible for arseniuretted 

 hydrogen (arsine) or similar products to be liberated from 

 compounds of arsenic are matters of considerable importance 

 from the public health point of view. Although wall-papers 

 coloured with an arsenic green are not so common as was 

 once the case, they may still be found, and, when exposed to 

 the air, may yield poisonous volatile compounds. At one 

 time it was commonly believed that cases of poisoning by 

 arsenical wall-papers were due to the dry dust given off from 

 the surface, but in 1908 it was proved by Gosio that the real 

 cause was an organic compound of arsenic produced by the 

 action of certain mould-fungi in the presence of the carbo- 

 hydrates contained in the paste by which the paper was 

 attached to the wall. 



This action is strictly specific, and was shown by Neppe 

 (Scienza Pratica, 1908, I, 82) to be a characteristic property 

 of the following moulds, arranged in the order of decreasing 

 activity: — Penicillium brevicaule, Aspergillus clavatus, 

 A. fumigatus, A. glaucus, A. virens, and Mucor mucedo. 



A certain degree of moisture is necessary for the action of 

 the mould-fungi, and a temperature of about 25° C. (77° F.) 

 promotes the decomposition, which appears to be a direct 

 vital phenomenon. When the amount of arsenic present 

 exceeds a certain proportion the mould-fungi themselves are 

 poisoned, but they can be gradually rendered immune to 

 larger quantities. The volatile compound set free was found 

 by Neppe to be diethyl-arsine, HAs (C2Hj) 2 . 



A further investigation of the moulds capable of decom- 

 posing arsenical compounds in this way has recently been 

 made by Dr. Husz (Apoth. Zeit., 1913, XXVIII, 605). The 



