An introduction to practical chemistry : including analysis . hole of theacid to precipitate in the form of sulphate of baryta(403), which, being insoluble in water, may be washedwithout loss, and when dry is weighed ; the weight ofthe sulphuric acid which it contains, may then be cal-culated from it (652). Precipitation is usually effected in upright glasses ofthe forms shown in Fig. 82. When precipitating asubstance in quantitative analysis, it is important thatsufficient of the precipitant is added to throw down thewhole of the substance affected by it, as otherwise adeficiency in weight wo
An introduction to practical chemistry : including analysis . hole of theacid to precipitate in the form of sulphate of baryta(403), which, being insoluble in water, may be washedwithout loss, and when dry is weighed ; the weight ofthe sulphuric acid which it contains, may then be cal-culated from it (652). Precipitation is usually effected in upright glasses ofthe forms shown in Fig. 82. When precipitating asubstance in quantitative analysis, it is important thatsufficient of the precipitant is added to throw down thewhole of the substance affected by it, as otherwise adeficiency in weight wouldbe occasioned: this is easilyascertained by adding adrop of the precipitant tothe solution filtered fromthe precipitate, which willcause a further precipitateif sufficient had not beforebeen added. When the precipitate is at all soluble, asthe bitartratc of potash, or ammonio-phosphate of mag-nesia, it is always advisable to allow the mixture tostand several hours before filtering, in order to insurethe separation of the whole of the required salt (184).. Precipitating Glasses. 208 OPERATIONS IN ANALYSIS. When the whole of the precipitate is thrown clown, itis separated from the solution either by filtration or dc-cantation (634, 643). Filtration. 634. The process of filtration is that most commonlyadopted for separating a precipitate from the solutionin which it was formed. The paper best adapted forthe purpose is a thin white blotting paper, which shouldbe free from visible holes, and should leave, when burnt,only a minute trace of inorganic matter. Such a papermay be purchased at any of the respectable dealers inchemical apparatus. It is convenient to keep a stock offilters ready cut, of a circular form, and of sizes varyingfrom three to ten inches diameter. These may be madeby having circular pieces of tin plate of the differentsizes, and scoring round them with a pencil upon thepaper, when several shepts may be cut through at oncewith scissors. 635. The filter, when req
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Keywords: ., bookcentury1800, bookdecade1850, booksubjectchemistry, bookyear18
