appearance. 3.
How may hard waters be softened for household purposes?

Experiment No. 44

Solvent Action of Water on Lead

Put 1 gm. of clean bright lead shavings into a test tube containing 10
cc. of distilled water. After 24 hours decant the clear liquid into a
second test tube, acidify slightly with HCL, and add a little hydrogen
sulphid water. A black or brownish coloration indicates lead in
solution.

(Adapted from Caldwell and Breneman, "Introductory Chemical Practice.")

Under what conditions may lead pipes be objectionable?

Experiment No. 45

Suspended Matter in Water

Place a drop of water on the microscopical slide, cover with cover
glass, and examine with the microscope. Note the occurrence and
appearance of any suspended matter in the water.

Experiment No. 46

Organic Matter in Water

Pour into the evaporating dish 100 cc. H_{2}O and evaporate to dryness
over the sand bath. Ignite the solids. If the solids blacken when
ignited, the water contains organic matter.

Experiment No. 47

Deposition of Lime by Boiling Water

Boil for a few minutes about 200 cc. of water in a flask. After the
water is cool, note any sediment of lime or turbidity of the water due
to expelling the carbon dioxid.

1. What is meant by a "hard" water? 2. What do the terms "temporary" and
"permanent" hardness of water mean? 3. What acts as a solvent of the
lime in water? 4. Why does boiling cause the lime to be deposited?

Experiment No. 48

Qualitative Tests for Minerals in Water

Test for Chlorids.--To 10 cc. of H_{2}O add a few drops of HNO_{3} and
2 cc. of AgNO_{3}. A white precipitate indicates the presence of
chlorids, usually in the form of sodium chlorid.

Test for Sulphates.--To 10 cc. of water add 2 cc. of dilute HCl and 2
cc. of BaCl_{2}. A cloudiness or the formation of a white precipitate
indicates the presence of sulphates.

Test for Iron.--If a brown sediment is formed in water exposed to the
air for some time, it is probably iron hydroxid. To 10 cc. of the water
add a few drops of HNO_{3}, heat, and then add 1/2 cc. of NH_{4}CNS. A
red color indicates the presence of iron.

Test for CaO and MgO.--To 10 cc. of H_{2}O add 5 cc. NH_{4}OH. If a
precipitate forms, filter it off, and to the filtrate add 3 cc. NH_{4}Cl
and 5 cc. (NH_{4})_{2}C_{2}O_{4}. The precipitate is CaC{2}O_{4}, and
the filtrate contains the magnesia. Filter and add 5 cc. Na_{3}PO_{4} to
precipitate MgNH_{4}PO_{4}