A manual of practical hygiene / by Edmund A. Parkes ; edited by F.S.B. Francois de Chaumont.

Date:
1878
Catalogue details

Licence: Public Domain Mark

Credit: A manual of practical hygiene / by Edmund A. Parkes ; edited by F.S.B. Francois de Chaumont. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

    111/820 (page 69)
    but Tiemann says that warming the water to 110° Fahr., will enable the smell to detect coal-gas, when chemical reagents fail. Generally there are other impurities, especially if it be derived from gas impregnation. In larger quantity it sometimes bubbles up from the water of stagnant pools, particularly it there be much vegetable matter; and in the cases of some natural sprincs m petroleum districts, can be ignited. Dissolved Solids. _ The discrepancies which are sometimes found in the consecutive analyses, or m analyses by two observers of the same water, probably arise from the diffi- culty of always separating the suspended matters. Consequently two samples apparently similar, may in reality contain variable quantities of suspended matters which affect the determination of the solids, or inauence other tests. lo avoid this source of fallacy, the water to be examined, if sedimentous, should be placed in a well-stoppered bottle in a dark place for 24 or 48 hours until all sediment has subsided, and the clear water should be then syphoned oft. If the sediment is too fine to subside, the water must be filtered through paper (previously well washed with weak hydrochloric acid, and then with distilled water, and then dried), but if possible filtration should be avoided. Ihe chemica] examination of the dissolved matters is divided into the qualitative and the quantitative. Qualitative Examination of Dissolved Solids st^nutl^ ^ eitter+!t/1T treated, oi, in the case of some con- stituents, it should be concentrated by evaporation. Water not Concentrated. Substance sought for. Reaction Lime Chlorine Reagents to be used and effects. Litmus and turmeric papers; usual red or brown re- actions. Oxalate of ammonium. White precipitate. Nitrate of silver, and dilute nitric acid. White precipitate becoming lead colour. Remarks. Sulphuric Acid Chloride of barium and dilute hydrochloric acid. White precipitate. Nitric Acid Brucine solution* and pure sulphuric acid. A pink and yellow zone. Usually neutral. If acid and acidity dis- appears on boiling, it is due to carbonic acid. If alkaline and disappears on boiling, to ammonia (rare). If perma- nently alkaline, to sodium carbonate. Six grains per gallon give turbidity ; sateen grains considerable precipi- One grain per gallon gives a haze ; four grains per gallon give a marked tur- bidity; ten grains a considerable precipitate. One-and-a-half grains of sulphate give no precipitate until after standing • three grains give an immediate haze,' and, after a time, a slight precipitate. The sulphuric acid should be poured gently _ down to form a layer under the mixed water and brucine solu- tion ; half a grain of nitric acid per gallon gives a marked pink and yellow zone; or.as recommended by Nicholson, 2 C.C. of the water may be evaporated to dryness ; a drop of pure sulphuric acid and a minute crystal of brucine be dropped in ; -01 grain per gallon can be easily detected, 'Brucine solution is made by dissolving one gTaniime in 1000 C.C. of distu^leTwaterT The