28 AXSWJEKS TO PRACTICAL 



HYDROSTATICS. 



I 1 9 ! Why can housekeepers test the strength of lye, 

 by trying ivhether or not an egg ivill float on it ? 



The potash dissolved in the water to form lye increases the 

 density of the liquid. When enough has been dissolved to make 

 its specific gravity greater than that of the egg, the egg will 

 float. This becomes, therefore, a simple but rough means of 

 testing the amount of potash contained in the lye. 



2. Hoiv much water will it take to make a gallon of 

 strong brine ? 



A gallon. The salt does not increase the volume of the 

 liquid. 



3. Why ought a fat man to swim more easily than a 

 lean one ? 



Because muscles and bones are heavier than fat. The spe- 

 cific gravity of a fat man is, therefore, less than that of a lean 

 one. 



0. If ^ve let bubbles of air pass up through a jar of 

 water 9 why will they become larger as they ascend ? 



The pressure of the water is less as they near the top, and 

 so they expand. 



7. IFJiat is the pressure on a canal lock-gate 14 feet 

 high and lOfeet wide, ^vhen the lock is full of water ? 



14 x 10 x 7 x 1,000 oz. = 980,000 oz. = 61,250 Ibs. 



8. Will a pail of ivater 'weigh any more with a live fish 

 in it than without ? 



If the pail were full before the fish was put in, then it will 

 make no difference, since the fish will displace its own weight 

 of water, which will run over. If the pail is only partially 

 filled, then, though the fish is upheld by the buoyancy of the 

 water, since action is equal to reaction, it adds its own weight 

 to that of the water. 



