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777. How are the metals distinguished from the nonmetals? Name some elements which cannot well be placed in either class.

778. To what substances was the name metalloid originally applied, and how is it now used ?

779. How would a chemist proceed to examine a new element so as to decide whether to class it with the metals or the non-metals ?

780. What is meant by each of the following terms applied to metals ? (a) tenacity, (6) malleability, (c) ductility, (d) lustre, (e) conductivity for heat and electricity.

781. How does increase of temperature usually affect (a) the malleability, (b) the tenacity, (c) the conductivity of metals ?

782. How would you obtain lead, tin, bismuth, silver, and potassium in well-defined crystals ?

783. Arrange in order of (a) fusibility, (6) ductility, (c) tenacity, (d) specific gravity, (e) conductivity, the following list of metals-iron, gold, mercury, silver, potassium, zinc, lead, lithium, platinum, antimony, copper, tin, and bismuth.

784. What property do you regard as most characteristic of the metals ?

785. When the terminals from a galvanic battery are placed in an easily decomposed metallic chloride, at which pole should the metal appear? How are the metals and metalloids classified from their electrical relations ?

786. Define the terms “specific heat” and “atomic heat." How would you ascertain the specific heat of mercury and of sodium ?

787. A kilogramme of mercury at 100° C. was mixed with one of water at jo° C. The temperature of the mixture fell to 12•°98 C. Find the specific heat of the mercury.

788. Describe Bunsen's ice calorimeter. 789. How does the determination of the specific heat of an element serve to control the determination of combining weight?

790. How may the atomic heat of an element be ascertained from the molecular heat of one of its compounds ?

791. What are alloys and amalgams? What is remarkable about the fusing point of alloys?

792. Explain the terms “atomicity of the elements” and “quantivalence of the metals.”

793. Arrange the elements in the order of their combining weights from hydrogen to bromine, and point out any coincidences which that arrangement suggests. 794. Give a

short account of Mendelejeff's researches on the connection between the atomic weights and the chemical and physical properties of the elements.

795. Point out how Mendelejeff's classification has aided chemical investigations.

796. Give a short history of the various researches on light which led to the introduction of spectrum analysis by Bunsen and Kirchhoff.

797. Hów has spectrum analysis advanced our knowledge (a) of the sun and stars, (6) of the metals, (c) of the distribution of the elements ?.

798. Describe the construction of a spectroscope, and explain how it is used for the detection of (a) metallic salts, (6) gases, (c) coloured liquids such as blood, solution of permanganates, &c. What are absorption spectra?

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