EXAMPLES. 135 



25. Two volumes, V and V, of different gases, at press- 

 ures p, p'> and temperature t, are mixed together ; the 

 volume of the mixture is U, and its temperature t'. Deter- 

 mine the pressure. p V + p' V 1 -+ at' 



^i YIS* r T -.. * ~ p 



U 1 + at 



26. Three gallons of water at 45 are mixed with six gal- 

 lons at 90. What is the temperature of the mixture ? 



An*. 75 



27. An ounce of iron at 120, and 2 oz. of zinc at 90, 

 are thrown into 6 oz. of water at 10, contained in a glass 

 vessel weighing 10 oz. What is the final temperature, 

 taking .1 and .12 as the specific heats of zinc and iron ? 



Ans. 13. 



