65% of 348. Expressed as a decimal, 65% = .65.

The weight

Another way of finding the amount of zinc is to subtract the weight of copper from the weight of the casting, or 348-226.2 = 121.8 lb. of zinc.

Rule. To find what per cent. of the whole is represented by a giver part, divide the part by the whole, and multiply the result by 100.

EXAMPLE.-A certain alloy contains 144 lb. of copper, 27 lb. of tin, and 9 lb. of zinc. Find (a) the per cent. of copper, (b) the per cent. of tin, and (c) the per cent. of zinc in the allpy.

SOLUTION.-The total weight of metal in the alloy is 144+27 +9=180 lb.

(a) There are 144 lb. of copper in 180 lb. of the alloy. Therefore, by the rule, 144÷ 180.8, and .8X100-80%; that is, there is 80% of copper in the alloy. Ans.

(b) There are 27 lb. of tin. and.15X100 = 15%; that is, Ans.

(c) There are 9 lb. of zinc. and .05X100=5%; that is, Ans.

Hence, by the rule, 27÷ 180=.15, there is 15% of tin in the alloy.

Hence, by the rule, 9180.05, there is 5% of zinc in the alloy.

METRIC SYSTEM

The metric system is based on the meter, which, according to the U. S. Coast and Geodetic Survey Report of 1884, is equal to 39.370432 inches. The value commonly used is 39.37 inches, and is authorized by the U. S. government. The meter is defined as one ten-millionth of the distance from the pole to the equator, measured on a meridian passing near Paris.

There are three principal units-the meter, the liter (pronounced lee-ter), and the gram-which are the units of length, capacity, and weight, respectively. Multiples of these units

are obtained by prefixing to the names of the principal units the Greek words deca (10), hecto (100), and kilo (1,000); the submultiples, or divisions, are obtained by prefixing the Latin words deci (), centi (o), and milli (robo). These prefixes

form the key to the entire system. In the following tables, the abbreviations of the principal units of these submultiples begin with a small letter, while those of the multiples begin with a capital letter; they should always be written as here printed.

MEASURES OF SURFACE (NOT LAND)

100 square millimeters (mm2.) = 1 square centimeter. 100 square centimeters. . . . . = 1 square decimeter. 100 square decimeters...... 1 square meter..

MEASURES OF VOLUME

.cm2.

.dm2.

..m2.

1,000 cubic millimeters(mm3.) = 1 cubic centimeter. 1,000 cubic centimeters.....=1 cubic decimeter. 1,000 cubic decimeters....

.cm3.

.dm3.

= 1 cubic meter.

..m3.

The liter is equal to the volume that is occupied by 1 cubic

decimeter.

The gram is the weight of 1 cubic centimeter of pure distilled water at a temperature of 39.2° F.; the kilogram is the weight of 1 liter of water; the ton is the weight of 1 cubic meter of water

METRIC CONVERSION FACTORS

1 milliliter.

1 centimeter.

1 meter..

1 kilometer.

1 inch..

1 foot.

1 yard. 1 mile..

MEASURES OF LENGTH

=.03937 in.

= .3937 in.
= 39.37 in.
=3.28083 ft.

= 1.0936 yd.
=3280.83 ft.
=1093.61 yd.
=.62137 mi.

= 25.4 mm.

= 2.54 cm.
= .254 m.
=304.8 mm.

= .3048 m.

= .9144 m.

= 1.609 km.

MEASURES OF AREA

1 square millimeter. 1 square centimeter..

1 square meter..

=.00155 sq. in.
=.155 sq. in.
= 10.764 sq. ft.
= 1.196 sq. yd.

1 liter.

= .4047 hec.
=2.5899 sq. km.

MEASURES OF VOLUME AND CAPACITY

1 cubic centimeter.

1 cubic meter...

1 cubic inch.

1 cubic foot.

1 cubic yard..

= 1 cu. dm.

61.023 cu. in.

= .0353 cu. ft.

=2.202 lb. water at 62° F.
= 1.0567 U. S. qt.
=.2642 U. S. gal.
=.061 cu. in.
=264.2 U. S. gal.
= 1.308 cu. yd.
=35.314 cu. ft.

= 16.387 cu. cm.
=28.317 cu. dm.
=28.317 1.
= .02832 cu. m.
=.7645 cu. m.

= 3.785 1.

1 U. S. gallon.

1 British gallon..

= 4.543 1.