Standard Methods for the Examination of Water and Sewage, Volume 2

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American Public Health Association., 1915 - Factory and trade waste
"The signature undertaking of the Twenty-Second Edition was clarifying the QC practices necessary to perform the methods in this manual. Section in Part 1000 were rewritten, and detailed QC sections were added in Parts 2000 through 7000. These changes are a direct and necessary result of the mandate to stay abreast of regulatory requirements and a policy intended to clarify the QC steps considered to be an integral part of each test method. Additional QC steps were added to almost half of the sections."--Pref. p. iv.
 

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Page 5 - One gram of this preparation in one liter of distilled water makes a stock suspension which contains 1000 parts per million of silica, and which should have a turbidity of 1000. Test this suspension, after diluting a portion of it with nine times its volume of distilled water, with a wire to ascertain if the silica has the necessary degree of fineness, and if the suspension has the necessary degree of turbidity. If not, correct by adding more silica or more water as the case demands.* Standards for...
Page 2 - Under many conditions, analyses made in the field are to be commended, as data so obtained are frequently preferable to those made in a distant laboratory after the composition of the water has changed en route. The allowable time that may elapse between the collection of a sample and the beginning of its analysis cannot be stated definitely, as it depends upon the character of the sample and upon other conditions, but the following may be considered as fairly reasonable maximum limits under ordinary...
Page 78 - Withdraw one cc of the sample with a sterilized pipette and deliver it into a sterilized Petri dish, 10 cm. in diameter. If there is reason to suspect that the number of bacteria is more than 200 per cc, mix one cc of the sample with nine cc of sterilized tap or distilled water.
Page 13 - ... 3 Distinct. An odor that would be detected readily and that might cause the water to be regarded with disfavor. 4 Decided. An odor that would force itself upon the attention and that might make the water unpalatable. 5 Very strong.
Page 79 - Expression of Results. — In order to avoid fictitious accuracy and yet to express the numerical results by a method consistent with the precision of the work the rules given below shall be followed: Numbers of Bacteria...
Page 3 - ... in connection with each determination. REPRESENTATIVE SAMPLES. Care shall be taken to secure a sample which is truly representative of the liquid to be analyzed. In the case of sewages this is especially important, in view of the marked variations in composition which occur from hour to hour. Frequently satisfactory samples can be obtained only by mixing together several portions collected at different times or at different places — the details as to collection and mixing depending upon local...
Page 110 - Place it, under side down, on a slide and protect it from dust. Prepare an emulsion, in sterile water, of the organism to be examined if it has been grown on a solid medium, or use a broth culture; spread the emulsion or broth upon the upper surface of the block as if making an ordinary cover-slip preparation.
Page 37 - ... steam begin to break at the surface of the water. The dish is then removed and the titration continued until a drop of the acid striking the surface of the liquid and sinking to the bottom of the dish produces no change in the uniform reddish or purple color of the solution. The number of cc of...
Page 26 - Allow the action to proceed for a minimum period of four hours, or over night. Pour the contents of the tube into a distilling flask, dilute with 250 cc of ammonia-free water, distill and collect in Nessler tubes and Nesslerize. When the nitrate content is high, collect the distillate in a 200 cc flask and Nesslerize an aliquot portion. If the supernatant liquid in the reduction tube is clear and colorless, the solution may be diluted to a definite volume and an aliquot part Nesslerized without distillation....
Page 110 - This will be found useful as a quick method of showing close relationships inside the genus, but is not a sufficient characterization of any organism. (2) The morphological characters shall be determined and described from growths obtained upon at least one solid medium (nutrient agar) and in at least one liquid medium (nutrient broth). Growths at 37 C shall be in genera] not older than 24 to 48 hours, and growths at 20 C. not older than 48 to 72 hours. To secure uniformity in...

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