104 ELEMENTARY GENERAL SCIENCE CHAP. 



and pressure ; (2) find the weight of an equal volume of gas under 

 the same conditions. Then 



Relative density of gas = observed weight of gas 



observed weight of hydrogen' 



QUESTIONS ON CHAPTER VII. 



1. State the principle of Archimedes. Describe an experiment 

 which illustrates the principle. 



2. What determines the distance to which a rectangular wooden 

 rod will sink when floated in a jar of water ? 



3. Describe an experiment to prove that when a rectangular 

 block of wood is floated in water the weight of the water 

 displaced by the portion immersed is equal to the weight of the 

 whole block. 



4. Give a few applications of the principle of Archimedes. 



5. Carefully distinguish between the following terms : density, 

 absolute density, relative density. 



6. Give a detailed description of the hydrostatic method of deter- 

 mining relative densities. 



7. A glass stopper is weighed in air and then immersed succes- 

 sively in water, beer, milk, and vinegar, and the loss of weight 

 noticed in each case. Explain how you would proceed to calculate 

 the relative densities of each of the liquids from these observations. 



8. How is the relative density of a liquid determined with a 

 specific gravity bottle ? 



9. Explain a simple method for ascertaining the relative density 

 of small shot or tin-tacks. 



10. Being provided with two pieces of glass tube and a piece of 

 india-rubber tubing, explain how you would proceed to (i) com- 

 pare the relative densities of olive oil and spirits of wine, (ii) ascer- 

 tain the relative density of a specimen of milk. 



11. Describe the instrument known as Hare's apparatus. What 

 advantages accrue from using it to determine the relative densities 

 of liquids. 



12. A piece of iron, weighing 275 grams, floats in mercury of 

 density 13 '59 -with of its volume immersed. Determine the 

 volume and density of the iron. 



13. The specific gravity of brass referred to water is 8 ; taking 

 the mass of 1 cubic foot of water as 1,000 ounces, find the density of 

 brass in ounces to the cubic inch. 



14. A cylinder whose base is a circle 1 foot in diameter, and 

 whose height is 3 feet, weighs 10 Ibs. Calculate its density, assuming 

 1 cubic foot of water to weigh 62 '5 Ibs. 



15. Of two bodies one has a volume of 5 cubic inches, the other of 

 one-fifth of a cubic foot ; in a perfectly just balance the former 

 weighs 15 oz., the latter 12*8 Ibs. What is the ratio of the mass of 

 the first to that of the second, and what is the ratio of the density of 

 the first to that of the second. 



16. If 100 cubic inches of oxygen (under certain circumstances of 

 pressure and temperature) weigh 35 grains, and a cubic inch of 



