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Analytical results and the collection of samples for water analysis
362
THE
H A R D N E S S OF L O N D O N WATERS.
T H E H A R D N E S S OF L O N D O N WATERS. I/~ 1894 the Thames water had 18"8 deg. of "hardness," the Lea 2o'1 deg, Kent 25"5 dee, and Colne Valley 7'4 deg. The term "hardness" is used to denote the proportion of carbonate of lime, or its equivalent of other soap-destroying substances, present in lO%OOO parts, by weight, of the water. The waters derived from the Thames and Lea, and the deep-wells of the Kent Company were a~l markedly softer than in recent years ; whilst the deep-well water of the East London Company and of the Tottenham Local Local Board of Health was of about the usual average hardness. The hardness of the metropolitan water supply is Mmost entirely due to the presence of bi-carbonate of lime in solution, which can be readily removed by treating the water with lime, as is successfully done by the Colne Valley Company. Thus the water pumped from the chalk by the Colne Valley Company is, originally, of about the same degree of hardness as the Kent Company's supply; but by treatment With lime before delivery, its hardness is reduced to about one-fourth of ks origirJal amount. The hardness of the river-water supplies can be reduced in the same manner. This mode of softening would appear to be the most economical, unless it can be shown that less than one: eightieth of the total supply is used for washing, for it entails only about one-eightieth of the expense incurred by the private consumer in the shape of additional soap.--ffr@ E. ffrank/and, bz the 28egislrar-Ge~zera?sAT~nu~[ S~mmary, 1894. A N A L Y T I C A L R E S U L T S A N D T H E COLL E C T I O N OF SA~{PLES F O R W A T E R ANALYSIS. TIaE relation between the amounts of organic carbon and organic nitrogen affords data from which an opinion may be formed as to the origin of the organic matter, whether animal or vegetable. I f the relative proportion of nitrogen to carbon be high, the inference is that the organic matter is chiefly animal ; on the other hand, if it be low, it is certain that the organic matter is chiefly, if not entirely, of vegetable origin. Examined from this point of view, the organic matter present in the river waters as delivered in London was to a very large extent of vegetable origin. In reference to this subject, the a~tention of the Local Government Board was recently called by the London County Council, to the discrepancy between nay results, as given in the tables in my former reports, and those furnished by the chemists who make analyses for the Metropolitan Water Companies, the results obtained by the Companies' chemists indicating that the organic matter present in the waters was chiefly of animal origin, whilst, as just mentioned, my analytical results assigned to it
chiefly a vegetable origin. At a consultation with, these chemists in the month of June last. it was. discovered that, owing to an error in the method of analysis pursued by the Companies' chemists~ they had obtained results which showed too large a proportion of nitrogen to carbon in the organic. matters. There had also been for a long time a considerable discrepancy between our analytical results in the case of the Chelsea Company's water,. the cause of which was discovered at the same t i m e . The assistant who collected the samples for the Companies' chemists, had, during two. years, inadvertently taken samples of the New River Company's water, believing them to be drawn from the Chelsea Company's main. Consequently the results reported as having been obtained by them with the Chelsea Company's water had, in fact, been got in the analyses o f water drawn from the New River Company's mains. These errors were at once remedied, and since that time our analytical results have been in close accordance.--~½"of 2~. ffrankland i~ the Registrar- General's Annual Summary, 1894. E F F E C T S OF S U N L I G H T ON T E T A N U S CULTURES, F. F. W~sa'~r~oor: (John Lucas Walker, student in Pathology, Cambridge), in Journal of Pathology and •acterio[ogy for November, 1894 , describes some of his experiments with tetanus spores. A cutture of tetanus-bacillus, grown three months in dextrose bouillon, was divided into two and placed in two specialIy contrived sterile pipettes, into one of which an atmosphere of hydrogen was introduced. Both were sealed and exposed freely to sunlight for nineteen days, then opened, fresh cultures made and two mice inoculated from each. The mice inoculated with the hydrogen culture both developed tetanus, those into which the same dose of the air culture had been injected were unaffected. From both pipettes typical cultures of the tetanus bacillus were obtained, and the culture from the pipette whose contents had been rendered harmless to mice by exposure to sunlight in air now killed mice in a shorter time than did its original parent culture. This lethal culture was again rendered harmless to mice by exposure to sunlight in air, and again t~ pical and lethal tetanus-bacilli developed from it. Very prolonged exposure to sunlight in air, however, not only destroyed the poison, but killed the spores. The amount of air surface to which the culture was exposed was shown by specially contrived experiments to be an important factor in rendering the growth harmless when exposed to sunlight. By an ingenious arrangement, Westbrook also showed that the prolonged exposure to sunlight in air was accompanied by an absorption by the gas in which the culture was exposed sufficient even to cause as much as two inches difference in the mercurial manometer.
THE
H A R D N E S S OF L O N D O N WATERS.
T H E H A R D N E S S OF L O N D O N WATERS. I/~ 1894 the Thames water had 18"8 deg. of "hardness," the Lea 2o'1 deg, Kent 25"5 dee, and Colne Valley 7'4 deg. The term "hardness" is used to denote the proportion of carbonate of lime, or its equivalent of other soap-destroying substances, present in lO%OOO parts, by weight, of the water. The waters derived from the Thames and Lea, and the deep-wells of the Kent Company were a~l markedly softer than in recent years ; whilst the deep-well water of the East London Company and of the Tottenham Local Local Board of Health was of about the usual average hardness. The hardness of the metropolitan water supply is Mmost entirely due to the presence of bi-carbonate of lime in solution, which can be readily removed by treating the water with lime, as is successfully done by the Colne Valley Company. Thus the water pumped from the chalk by the Colne Valley Company is, originally, of about the same degree of hardness as the Kent Company's supply; but by treatment With lime before delivery, its hardness is reduced to about one-fourth of ks origirJal amount. The hardness of the river-water supplies can be reduced in the same manner. This mode of softening would appear to be the most economical, unless it can be shown that less than one: eightieth of the total supply is used for washing, for it entails only about one-eightieth of the expense incurred by the private consumer in the shape of additional soap.--ffr@ E. ffrank/and, bz the 28egislrar-Ge~zera?sAT~nu~[ S~mmary, 1894. A N A L Y T I C A L R E S U L T S A N D T H E COLL E C T I O N OF SA~{PLES F O R W A T E R ANALYSIS. TIaE relation between the amounts of organic carbon and organic nitrogen affords data from which an opinion may be formed as to the origin of the organic matter, whether animal or vegetable. I f the relative proportion of nitrogen to carbon be high, the inference is that the organic matter is chiefly animal ; on the other hand, if it be low, it is certain that the organic matter is chiefly, if not entirely, of vegetable origin. Examined from this point of view, the organic matter present in the river waters as delivered in London was to a very large extent of vegetable origin. In reference to this subject, the a~tention of the Local Government Board was recently called by the London County Council, to the discrepancy between nay results, as given in the tables in my former reports, and those furnished by the chemists who make analyses for the Metropolitan Water Companies, the results obtained by the Companies' chemists indicating that the organic matter present in the waters was chiefly of animal origin, whilst, as just mentioned, my analytical results assigned to it
chiefly a vegetable origin. At a consultation with, these chemists in the month of June last. it was. discovered that, owing to an error in the method of analysis pursued by the Companies' chemists~ they had obtained results which showed too large a proportion of nitrogen to carbon in the organic. matters. There had also been for a long time a considerable discrepancy between our analytical results in the case of the Chelsea Company's water,. the cause of which was discovered at the same t i m e . The assistant who collected the samples for the Companies' chemists, had, during two. years, inadvertently taken samples of the New River Company's water, believing them to be drawn from the Chelsea Company's main. Consequently the results reported as having been obtained by them with the Chelsea Company's water had, in fact, been got in the analyses o f water drawn from the New River Company's mains. These errors were at once remedied, and since that time our analytical results have been in close accordance.--~½"of 2~. ffrankland i~ the Registrar- General's Annual Summary, 1894. E F F E C T S OF S U N L I G H T ON T E T A N U S CULTURES, F. F. W~sa'~r~oor: (John Lucas Walker, student in Pathology, Cambridge), in Journal of Pathology and •acterio[ogy for November, 1894 , describes some of his experiments with tetanus spores. A cutture of tetanus-bacillus, grown three months in dextrose bouillon, was divided into two and placed in two specialIy contrived sterile pipettes, into one of which an atmosphere of hydrogen was introduced. Both were sealed and exposed freely to sunlight for nineteen days, then opened, fresh cultures made and two mice inoculated from each. The mice inoculated with the hydrogen culture both developed tetanus, those into which the same dose of the air culture had been injected were unaffected. From both pipettes typical cultures of the tetanus bacillus were obtained, and the culture from the pipette whose contents had been rendered harmless to mice by exposure to sunlight in air now killed mice in a shorter time than did its original parent culture. This lethal culture was again rendered harmless to mice by exposure to sunlight in air, and again t~ pical and lethal tetanus-bacilli developed from it. Very prolonged exposure to sunlight in air, however, not only destroyed the poison, but killed the spores. The amount of air surface to which the culture was exposed was shown by specially contrived experiments to be an important factor in rendering the growth harmless when exposed to sunlight. By an ingenious arrangement, Westbrook also showed that the prolonged exposure to sunlight in air was accompanied by an absorption by the gas in which the culture was exposed sufficient even to cause as much as two inches difference in the mercurial manometer.