FREE BOOKS

Author's List




PREV.   NEXT  
|<   76   77   78   79   80   81   82   83   84   85   86   87   88   89   90   91   92   93   94   95   96   97   98   99   100  
101   102   103   104   105   106   107   108   109   110   111   112   113   114   115   116   117   118   119   120   121   122   123   124   125   >>   >|  
then he glanced at his watch. "Is that scum the elutriation?" said Tom, with a faint grin. "No, boy, the impurity; throw it down the sink. Now, Tom, we want to get our finest polishing emery out of that mixture, and it will take an hour to form--sixty-minute emery, the opticians call it; so while it is preparing, we'll go and have another turn at the speculum." They descended, leaving the pan standing on the heavy table, and after spreading wet sand upon the lower disc of glass, the loose one was once more set in motion, and uncle and nephew, with quarter-hour rests for examination and wetting the surfaces, patiently ground away for an hour, by which time, upon the speculum being sponged, it was found that the greater part of the upper glass was deeply scratched. "This is going to be an awfully long job," thought Tom. "Yes, it is," said his uncle, who aptly read his thoughts, "a very long job, Tom; but good things have to be worked for, boy." "Oh, I'm not going to be tired, uncle. It's like working for a grand prize." "It is. Now then, let's see to the emery. Our finest must be ready by now. Now I want all the water, from which the emery has settled down to the bottom, drawn off into that great white basin. How is it to be done?" "Pour it off," said Tom. "No; couldn't be done without disturbing the bottom. Let's try syphoning." Uncle Richard placed the basin upon a stool below the level of the table, took up a glass tube bent somewhat in the shape of a long-shanked hook, placed the short end gently beneath the surface of the nearly clear water, his lips to the long end, drew out the air, and the water followed directly from the atmospheric pressure, and ran swiftly into the basin. As it ran, and Tom watched, Uncle Richard carefully held the short arm of the syphon, guiding it till the sediment at the bottom of the pan was nearly reached, when he quickly withdrew it, and the basin was then placed beside the pan. "There, Tom," said Uncle Richard, "that's our sixty-minute emery." "But I thought you said you wanted it very fine. You've only washed it." "We're playing at cross purposes, Tom," said Uncle Richard. "You are talking about the contents of the pan, I about those of the basin." "What! the clear water--at least nearly clear?" "Ah, there you have hit it, boy--nearly clear. That water contains our finest polishing powder, and it will have to stand till to-morrow to settle
PREV.   NEXT  
|<   76   77   78   79   80   81   82   83   84   85   86   87   88   89   90   91   92   93   94   95   96   97   98   99   100  
101   102   103   104   105   106   107   108   109   110   111   112   113   114   115   116   117   118   119   120   121   122   123   124   125   >>   >|  



Top keywords:

Richard

 

bottom

 

finest

 
thought
 
polishing
 

minute

 
speculum
 

elutriation

 

standing

 

surface


gently
 

beneath

 

directly

 

watched

 

carefully

 
swiftly
 

atmospheric

 

pressure

 

syphoning

 
impurity

disturbing

 
shanked
 

syphon

 

descended

 

contents

 

talking

 

playing

 
purposes
 

morrow

 

settle


powder

 

quickly

 

withdrew

 

reached

 

sediment

 

couldn

 

guiding

 

washed

 

glanced

 

wanted


sponged

 

greater

 

deeply

 

opticians

 

scratched

 

ground

 
patiently
 

motion

 

examination

 

wetting