716 



SCIENCE 



[N. S. Vol. XXXVIII. No. 



sulphur broken down in simple peptone media by 

 the so-called putrefactive bacteria, of the forms of 

 sulphur most readily used by them and of the forms 

 in which the sulphur exists after the action of the 

 bacteria, whether as fixed sulphur, or as loosely 

 bound sulphur, or as easily oxidized sulphur, or as 

 a volatile sulphur compound such as hydrogen sul- 

 phide, when culture fiasks of different size and 

 shape were used and when air or carbon dioxide 

 was passed over the cultures. 



E. M. Chamot: The Value of Testing for Hydro- 



gen Sulphide Production in the Bacteriological 



Examination of Potable Waters. 

 E. M. Chamot and H. W. Eedfield: A Study of 



the Best Conditions for Sydrogen Sulphide 



Production in Peptone Media. 



The method for the detection in water of the 

 bacteria producing hydrogen sulphide has been 

 studied in a systematic manner as regards the con- 

 centration of possible ingredients, and a culture 

 medium has been devised by the use of which the 

 time required in which to get evidence of the 

 presence of these organisms has been greatly 

 reduced. 



The method furnishes a means of detecting cer- 

 tain organisms which do not produce gas in lactose 

 media, but which are found in sewage-polluted 

 water. 



E. M. Chamot and R. C. Lowary: The Influence 



of the Composition of Carbohydrate Culture 



Media on the Amount and Character of the Gases 



formed by Fecal Organisms. 



E. M. Chamot and C. M, .Sherwood: A Study 



of the StoTces Neutral Bed Beaction. 

 J. Culver Haetzell: Further Notes on Standards 

 of Potable Waters. 



In this paper the author states that he has col- 

 lected further data on the necessity for regional 

 standards of potable waters, and that the feeling 

 is growing that standards are not only possible and 

 desirable, but necessary. 



Atheeton Seidell and Philip W. Meseeve: Tlie 

 Determination of Minute Amounts of Sulphur 

 Dioxide' in Air. 



The amounts of sulphur dioxide which it was 

 desired to determine varied from about 1 to 15 

 parts per m.illion, which is about the concentration 

 just detectible by the odor. Experiments showed 

 that at this dilution, various modifications of the 

 iodine titration methods, involving the use of an 

 excess of iodine and back titration directly or with 

 an excess of thiosulphate and then to appearance 

 of the bine starch color with iodine, were imprac- 



tical on account of the variability of the end point 

 when approached in opposite directions. It was 

 found that satisfactory results could be obtained by 

 adding about 5 c.c. of water containing starch 

 paste to the 2,500 c.c. bottle containing the sample 

 and titrating to appearance of the blue starch color 

 with A'^/1,000 iodine. A correction for the blank 

 determination in the bottle containing air free from 

 sulphur dioxide, and one for the apparent incom- 

 pleteness of the reaction at this dilution must be 

 appUed. With these corrections for a 2,500 e.c. 

 bottle, 1 o.e. of N/lfiOO iodine corresponds to 4.1 

 parts SO, per million. On account of the rapid 

 oxidation of SO, to SO3, even in bottles as dry as 

 can conveniently be obtained, it is necessary to 

 make the titrations within a short time after col- 

 lecting the samples. When relatively minute 

 amounts of SO2 are liberated in rooms and the air 

 actively stirred, less than one half the calculated 

 percentage in the air has so far been found. The 

 complete disappearance of the liberated SO2 may 

 occur in less than one half hour, depending upon 

 the amount of moisture, nature of walls, ete. 

 J. W. Sale and W. W,. Skinner: Comparison of 

 Methods for the Determination of Dissolved 

 Oxygen. 



A comparison of the Winkler and modified Levy 

 methods with the gasometrio method for the deter- 

 mination of dissolved oxygen indicates that in pure 

 and moderately polluted saline waters the Winkler 

 method gives accurate results while the Levy 

 method gives results that are too low. The Winkler 

 method also gives closely agreeing results in dupli- 

 cate and triplicate determinations on such waters, 

 for the most part within .02 c.c. oxygen per liter. 

 Only that modification of the Levy method in 

 which sodium carbonate is used to precipitate the 

 iron salts was compared. 



W. D. Collins and W. W. Skinner: The Quanti- 

 tative Use of the Spectroscope in Water Analyses. 

 By careful attention to details of manipulation 

 described in the paper quantitative results for 

 lithium and potassium may be obtained by use of 

 the spectroscope in very much less time than is 

 required for separation of the alkalies in a water 

 analysis. The errors may be 5-10 per cent, of the 

 amounts determined. The results in connection 

 with other quickly made determinations make pos- 

 sible the furnishing of a fairly complete water 

 analysis with a comparatively small amount of 

 work. 



F. L. Rector: Longevity of B. Typhosus in Water. 

 Charles L. Parsons, 



Secretary 



