May 1, 1865.] THE TECHNOLOGIST. 



OIL FOR WATCHES. 465 



consider that oil, to be good, must always retain the same colour after 

 being applied to the watch; probably, more judge by this than any 

 other thing. If it is found to turn green after ten or twelve months, it 

 is considered as bad. Now, in some cases, it may be a sign of badness, 

 but in others it is quite fallacious ; for although it will be found that 

 the thick, gummy oil is always green, it will also be found that oil 

 which becomes green does not always get into a thick state, but may 

 keep quite liquid. 



In all my experiments with oils, I have never yet got one which 

 will remain on a piece of brass for a year without becoming green ; and 

 knowing that the colour of the oil cannot have the least effect on the 

 going of a watch, I have given up considering the changing of colour as 

 a sign of badness. Oil to be good should not freeze too readily. If an 

 oil get thick before the thermometer reaches freezing-point, I consider 

 it congests too easily, but if at that degree of cold it retains its fluidity, 

 it is all that is needed ; for, although during winter the cold is often 

 below freezing-point, a watch movement being not only kept within a 

 case, but having also various other shelters, will seldom or ever be sur- 

 rounded with air so cold as 32 deg. 



The requisite conditions of good oil are then — first, that it does not 

 get into a gummy state when applied to the watch ; second, that it does 

 not dry up ; third, that it does not spread over the plate ; fourth, that 

 it does not freeze too readily. 



The next question is, What are the best tests for ascertaining good 

 oil 1 Some will say, " Apply it to a watch, and try it." This, no doubt, 

 is a very good plan, but it involves a considerable amount of attention ; 

 it eannot be decided in a week or a month, unless it be notoriously bad 

 It is too serious a matter to term this a wise plan for ascertaining the 

 quality of an oil. There seems to be considerable difference of opinion 

 amongst watchmakers as to the best test for oils. Some test it by its 

 colour ; if it is clear, it gains their confidence. Others, again, prefer it 

 with colour. Some like it thick, others very thin. Some taste it ; 

 others smell it ; while some try it by taste, smell, and colour. Others, 

 again, who find that their oil does not freeze in snow consider it perfect. 

 Such are the various tests which are employed by watchmakers to ascer- 

 tain whether oil is good or bad. 



Having experimented for many years with watch-oils, I consider the 

 best and safest plan to test the quality is to take several pieces of brass ; 

 make small countersinks in each piece, put a little oil into each sink ; 

 then place the pieces of brass away where they will be free from dust ; 

 and if at the end of twelve months the oil remains fluid, it may be used 

 with all safety. This may seem a very tiresome way of testing oil, but 

 I know of no other sufficient to attain the object ; a shorter time will 

 not suffice. I have found some oils keep very well for eight or nine 

 months, and after that period they rapidly become thick and bad. It 

 will be found that oil keeps better on a gilt watch-plate than on a piece 



