Saunier states[17] that "success depends largely on the skill of the manipulator; and if he is not endowed with the power of judging, _mainly by the taste_, whether oil satisfies certain prescribed conditions, he can never be certain of the result." As the author's abilities in this regard are not up to the required standard, and as some oils are sometimes in such a state of decomposition that even the odor is unpleasant, he has used other, and perhaps more satisfactory, methods of determining the relative values of the various oils. The following experiments show the relative values of oils that have been, or may be, used in horology: J. J. Redwood has made experiments on the action of oils upon metals, especially for the purpose of determining which oils were best adapted for use on the various metals and for ascertaining which oils were most suitable for mixing as lubricants. He has tabulated the results of his researches in two tables, which show that:[18] _Mineral oil_ has no effect upon copper and zinc, and attacks lead most. _Olive oil_ attacks copper most, tin least. _Sperm oil_ attacks zinc most, copper least. The experiments show, on the other hand, that: _Brass_ is attacked most by olive oil. _Copper_ is not attacked by mineral lubricating oil, least by sperm oil.[19] Dr. Watson states in regard to this action: 1. That of the oils used, viz., olive sperm, neat's-foot, and paraffine, the samples of paraffine oil on copper was least affected, and that sperm was next in order of inaction. 2. That the appearances of the paraffine oil and the copper were not changed after an exposure of 77 days. He later[20] experimented further with the following results noted, after one day's exposure, with iron:-- 1. _Neat's-foot._--Considerable brown irregular deposit on metal. The oil slightly more brown than when first applied. 2. _Sperm._--Slight brown deposit with irregular markings on the metal. Oil of dark brown color. 3. _Olive._--Clear and bleached by exposure to light and air. The appearance of metal the same as when first immersed. 4. _Paraffine._--Oil bright yellow and contains a little brown deposit. The action of oils on iron exposed to their action for twenty-four hours and on copper after ten day's exposure was found to have been:-- TABLE II. ACTION OF OILS ON METALS. ------------+----------------+----------------- OILS. | IRON DISSOLVED | COPPER DISSOLVED | IN 24 HOURS. | IN 10 DAYS. ------------+----------------+----------------- Neat's foot | .0875 grain. | .1100 grain. Sperm | .0460 " | .0030 " Olive | .0062 " | .2200 " Paraffine | .0045 " | .0015 " ------------+----------------+-----------------