154 'APPLIED SCIENCE 



171. Requirements of a Good Lubricant. The selection 

 of the proper lubricant in any particular case depends, of 

 course, upon the class of machinery in which it is to be used. 

 If on light-running and high-speed machinery, such as is 

 used in the spinning, twisting, and other departments of 

 textile mills, the light-bodied or more fluid oils give the best 

 results. For slow-speed machinery, the heavier bodied oils 

 are best. For use on slow-speed engines, where the oil is 

 fed from cups, a heavy-bodied oil should be used. For high- 

 speed work and engines where continuous oiling systems are 

 used, a light-bodied oil is preferable. Cylinder oils have 

 for their base what is known in the oil trade as cylinder 

 stock, of which there are two classes the light-colored or 

 filtered stock, and the dark or steam-refined stock, the latter 

 being almost universally used. 



For steam turbine lubrication, a high-grade, pure mineral 

 oil is best, as the oil is subjected to high pressure and constant 

 churning, and consequently must be of good quality. 



For gas cylinder lubrication, a pure mineral oil ranging 

 in body from light to heavy is found most satisfactory. This 

 type of oil burns freely without leaving a carbon ash. 



Questions 



1. What is a solution? 



2. Will a cold solution dissolve more of a substance than a 

 hot solution? 



3. What is n solvent? Name two or three common solvents. 



4. What is a saturated solution? How are you able to tell if 

 a solution is saturated or not? 



6. What is ebullition? 



6. What is precipitation? Has it any industrial importance? 



7. Explain the difference between a sediment and u precipitate? 



8. What is clarification? 



