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SPECIFIC GRAVITY.

SPECIFIC GRAVITY. 57. The specific gravity of a substance is the quotient obtained by dividing the weight of a given volume of the substance by the weight of an equal volume of water.

58. This quotient has been ascertained by experiment for a great variety of substances, and some of the more useful results are given in the following

..............

Table of Specific Gravities. Alcohol, absolute ... ... ... ... 0.795 | Maple-wood ... ... ... ... ... ... ... 0.790 Ash-wood ..... ................... 0.845 Marble ...................2.65 to 2.75 Beech-wood................... 0.852 Mercury ..........................13.596 Brass, cast ... ... ... ... ......... 7.820 Milk ............................... 1.031 Brass, sheet .............. 8.390 Muriatic acid ..................

1.200 Brick ..............

2.000

Naphtha ......................... 0.840 Chestnut-wood ................ 0.565 Nitric acid....................... 1.500 Copper, hammered ............ 8.900 | Oak, green ..................... 1.113 Cork ................................. 0.240 Oak, seasoned .................. 0.743 Diamond ......................... 3.530 Olive oil.......................... 0.915 Ether, sulphuric .............. 0.715 Pine-wood, hard. .............. 0.657 Ebony .. ... ... ... ... ... ... ... ... ... 1.331 Pine-wood, white .............. 0.551 Glass, flint ...................... 3.000 Platinum, hammered .........22.060 Glass, crown .................... 2.520 Proof spirit ... . . . . . . . . . . . . . . . ... 0.920 Gold, hammered .............. 19.350 Sandstone ..............2.25 to 2,65 Granite .................. 2.65 to 2.75 Sea-water ....................... 1.025 Ice .................................. 0.918 Silver, hammered .............10.510 Iron, cast ........................ 7.250 Steel, soft ........................ 7.830 Iron, wrought .................. 7.780 Steel, tempered ............... 7.810 Lead, cast... ... ... ... ... ... ... ... 11.350

...................11.350 Sulphuric acid ................. 1.841 Lignum Vitae ................... 1.333 Tin, cast ......................... 7.290 Limestone ...............2.60 to 2.70 Wax.....

0.960 Mahogany-wood ............... 1.063 | Zinc. ............ .............. 7.190

59. Since a cubic centimeter of pure water weighs 1 gram, a cubic decimeter 1 kilogram, and a cubic meter 1 metric ton, the numbers in a table of specific gravities show

(1) the weight in grams of one cubic centimeter) (2) the weight in kilograms of one cubic deci- (of any given meter (one liter)

substance. (3) the weight in metric tons of one cubic meter J

60. From the above statement may be deduced the fol

lowing

Rules. 1. To find the weight of a substance when its volume is known: Multiply the volume by the specific gravity:

2. To find the volume of a given substance when its weight is known : Divide the weight by the specific gravity.

61. Examples. 143. What is the weight in kilograms of a cubical piece of cast-iron measuring 12 cm each way?

144. What is the weight in kilograms of a cannon-ball of cast-iron 17.5 cm in diameter ?

145. What is the diameter of a lead bullet of spherical shape weighing 14 grams ?

146. What is the weight of a load of bricks, the number of bricks being 1000, and the dimensions of each 19 cm long, 8.7 cm wide, and 6 cm thick?

147. The front wall of a warehouse extending 15" along the street is of granite, and is supported on iron columns. Find the pressure in metric tons on these columns, supposing the walls to be on the average 50 cm thick and to rise 12.5 m above the columns, and making no allowance for windows.

148. A bottle weighing 254 grams when empty holds

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1.34 liters. What will it weigh when filled with sulphuric acid ?

149. A bottle weighs 803 grams when filled with sulphuric ether and 241 grams when empty. What is the capacity of the bottle in liters ?

150. What is the weight in kilograms of a maple plank 4.3 m long, 63 cm wide, and 7.9 cm thick ?

151. How many cubic centimeters of water would be displaced by a cubic decimeter of white-pine wood floating in it? What fraction of the block would remain above water ?

NOTE. A solid body floating in a liquid sinks far enough to displace its own weight of the liquid.

152. What part of an iceberg floating in the ocean would be under water ?

153. A bar of wrought-iron floats in mercury. What part of it is below the surface of the mercury ?

154. A solid floating in water is below water. What is the specific gravity of the solid ?

155. A bottle holding just 750 cubic centimeters, and weighing when empty 157 grams, is filled with a certain liquid and is then found to weigh 976.5 grams. Find the specific gravity of the liquid.

156. Wishing to ascertain the specific gravity of a piece of metal weighing 1432 grams, I sink it in a vessel that is just full of water and take it out again. Before this was done the vessel full of water weighed 512 grams, but afterwards it weighed only 357 grams. What was the specific gravity of the metal ?

157. A piece of wood 1 m long, 30 cmn wide, and 10 cm thick, is found to weigh 16.95 K. What is the specific gravity of the wood ?

158. A granite obelisk 1" square at the base, 60 cm square at the top, and 6" high, terminates in a pyramid 30 cm high, making the total height of the obelisk 6.30 m. What is the weight of this obelisk in kilograms?

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Ex. Ans. 1. 0.1 m. 2. 1.3 m. 3. 21.4 m. 4. 0.01 m. 5. 0.38 m. 6. 5.29 m. 7. 0.001 m. 8. 0.048 m. 9. 3.675 in. 10. 4,250 m. 11. 3,500 m. 12. 23,500 m. 13. 9,460 m. 14. 9,240 in. 15. 397 m. 16. 720 m. 17. 7.3 m. 18. 50 m. 19. 67.678 m. 20. 649.115 m. 21. 415,990 m. 22. 5.26749 Km. 23. 35,000 m. 24. 86.62 m. 25. 15,480 m. 26. 71 m. 27. 73.50672 Km. 28. 22. 2075 m. 29. 300 times. 30. 23.85 sq. m. 31. 20 m. 32. $ 8.40. 33. 217.5 ca. ; 2.175 a. 34. 4,585.76 a. 35. $6,556.57. 36. 12.043044049 cu. m. 37. 153.41 cu. m. 38. $ 373.721. 39. 369.6 loads. 40. $29.25. 41. 12 m.; $20.25. 42. 20%. 43. $ 1.23. 44. 751. 45. 39 Hi. 46. 4.5 m. 47. $ 3.09. 48. $ 2.31. 49. 135 grams. 50. 5.4 T. 51. 15,744 ft. 52. 31.0685 m.

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| Ex. Ans. 105. 77.2 K. 106. 105.4 K. 107. 4,562 kilogram-meters. 108. $ 1,440. 109. 21 m. 110. 1,943.76 sq. m. 111. 0.8494 sq. m. 112. 742.9 sq. m. 113. 1,662.3 a. 114. 4.8356 sq. in. 115. 167 7 sq. dm. 116. 1.20 m. 117. 5.64 m. 118. 42.5 cm. 119. 9.625 a. 120. 19.8 cu. m. 121. 99.792 1. 122. 65.7 cm. 123. 10.362 1. 124. 503.1. 125. 399.3. 126. 294.2. 127. 233.5. 128. 185.3. 129. 136.6. 130. 108.4. 131. 86.0. 133. 50.3. 132. 63.4. 134. 39.9. 135. Dia. 108.4; dep. 216.7. 136.

86.0; “ 172.0. 137. 68.3; “ 136.6. 138. " 50.3; “ 100.6. 139. " 39.9: “ 79.9. 140.

63.4. 1.1. 23.4: " 46.7. 122. “ 18.5; " 37.1. 143. 12.528 K. 144. 20.345 K. 145. 13.3 mm. 1.46. 1,983.6 K. 147. From 248 to 258 T. 148. 2.721 K. 149. 0.786 l. 150. 169.07 K. 151. 551 cu. cm. ; 4400 152. 0.8956, or about io. 153. 0.572. 154. 6 or 0.833. 155. 1.093. 156. 9.24. 157. 0.565. 158. From 10.48 to 10.88 T.

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