446 ABSTRACTS OF CHEMICAL PAPERS BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. Culture Media employed for the Bacteriological Examination of Water. 11. : Lactose-Peptone Media. E. M. Chamot and H. W. RedAeld. ( J . Amer. Chem. SOC., 1915, 37, 1949-1958.)-1n the fermentation of lactose by bacteria in water contaminated by sewage, human faeces, the faxes of domestic animals, and pure strains of the B.coZi group, the total volume of gas formed increases to a, final maximum with the concentration of the peptone, meat, liver, or meat extract, employed. The composition of the gas formed is dependent upon the concentration of the nitrogen-containing substance employed. The addition of from 0-5 per cent. to I per cent. of potassium chloride to lactose-peptone media appears to stimulate fermentation and assure more uniform results.Similar beneficial effects are obtainable with sodium chloride, but of not so marked a character. Nothing is to be gained by employing a lactose concentration of over 1 per cent. Neutral media appear to yield slightly greater gas volumes than media, slightly acid to phenolphthalein ; but media, having a reaction of approximately + 1 per cent. ferment considerably more rapidly, and yield diagnostic results in several hours’ shorter time.The gas ratios of the 23. coli group are dependent upon the concentra- tion of the peptone or other similar nitrogenous material in the media. The addition of meat infusion to peptone media is of advantage when low concentrations of peptone are employed, but yields media whose reactions rapidly change.A very sensitive peptone culture medium yielding uniform results and large gas volumes consists of peptone 3 to 4 per cent., lactose 0.8 per cent., potasRium chloride 0.6 per cent. ; reaction + 1 per cent. Such media show little change on keeping. H. F. E. H.BACTERIOLOGICAL, PHY STOLOGICAL, ETC. 447 Detection of Hydrocyanic Acid. P. Lavialle and L.Varenne. ( J . Phamm. Chim., 1915, 12, 74-81.)-The solution containing hydrocyanic acid or alkali cyanides is treated with a slight excess of cold ammonium hydrosulphide gently boiIed for about five minutes, and then evaporated to about 1 C.C. on the water- bath. The residue is taken up with 9 C.C. of water, 10 drops of hydrochloric acid .added, and the liquid shaken with three successive portions (20 c.c., 10 c.c., and 10 c.c.) of ether.The united ethereal extracts are evaporated at the ordinary temperature, and the residue (from which all odour of ether must have dis- appeared) is immediately tested and stirred with ferric chloride solution (French offhinal solution diluted with 9 parts of water). The blood-red coloration of iron thiocyanate will be obtained with solutions which originally contained only 0*00005 grm.of hydrocyanic acid, so that the test is about twenty times as sensitive as the Prussian blue reaction. The iron thiocyanate can be distinguished from irori meconate by being decolorised by 10 per cent. gold chloride solution (cf. Lander and Walden, ANALYST, p. 1911, 36, 266). C. A. M. Toxicity of Various Wood Preservatives.R. M. Fleming and C. J. Humphrey. (J. Ind. and E y . Chem., 1915, 7, 652-658.)-A small sterilised measured quantity of the preparation to be investigated is mixed with a convenient volume of a sterile medium made from lean beef, malt extract, and agar. The mixture is then poured into a Petri dish, and, after cooling, the plates are inoculated in the centre with a preparation of mycelium, 6 mm.square, from cultures of Foms unnosus two to three weeks old. The plates are then incubated at 25' C. for six weeks, and the growth of the culture is measured. The toxicity not only varies with the medium into which the preservative is introduced, but also with the organism, and in general it is found that yeast and moulds are less sensitive to toxic substances than wood-destroying fungi.Fomes annosus was selected because of its very destructive effect upon coniferous wood, particularly in mines ; because of its wide distribution ; and since it grows well on the agar medium employed. The age of the growth employed for the inoculation makes a considerable difference in the activity of its growth on a toxic medium, the advantage always being with the younger culture.Another factor influencing the growth of the organism on the plate is the previous environment of the organism ; for if this has been taken from a toxic medium the subsequent growth of the organism is considerably strengthened, acclimati8ation having rendered the mycelium capable of a more vigorous growth. The results of a large number of experiments are tabulated, for which the original paper must be consulted.Of the wood distillates, the beech-wood creosote proved highly toxic, being two to three times as effective as average coal-tar creosote. Other wood distillates proved to be only one-half to one-third as toxic as coal-tar creosote. The more highly toxic constituents of coal-tar creosote would appear to have their boiling-points between 215" and 305" C., while, of the two water-gas-tar distillates experimented with, the distillate of lowest sp.gr. (0.995) was somewhat less toxic than coal-tar creosote, while that of high sp. gr. (1.042) fell comparatively low in the scale.448 ABSTRACTS OF CHEMICAL PAPERS Zinc sulphate compares very favourably with zinc chloride, and also with coal- tar creosote. When drawing comparisons between zinc chloride and the Bruening and Marmetschke solution (zinc chloride and aluminium sulphate), it should be remembered that zinc chloride cannot be tested satisfactorily by mixing with ordinary nutrient agar, on account of its tendency to combine with the medium. The three petroleum oils tested showed but slight or no toxic qualities, in that generally 40 per cent. cultures nearly equalled, and sometimes even excelled, the growth on the control cultures. H. F. E. H.