Weekly journal-miner., 1915-08-11
EXPLAINS CAUSE
 OF CARBON DEPOSITS

S~NN~@ OAN 04S1 S01 ! O
 Lieutenant c. S.Bryan, government expert, in an article in the February issue of the Journal of the American Society of Naval Engineers, says:
 Carbon may exist in motor oil in two forms: First, as free carbon held in suspension, and, second, in combination with hydrogen, forming the numerous hydrocarbon com pounds which go to make up the oil. The amount of free carbon in a we'll refined oil is very small, and the ob- jectionabie carbon deposit is gener- ally due to some other factor.
 The conditions attained in the cylinder of internal combustion en- zines that result in the formation of carbon are: First, high temperature, and, second, limited supply of oxy- gen (air). References have been made to oil burning This term has been used rather loosely, as strictly speaking, burning means the com bining of the vapors from the oil with the oxygen of the air, and does not include simple repatriation of the oil. Unless air is present in excess of that required for the combustion of the gasoline or fuel oil, and us ually 1t is not, the oil cannot really burn. Under the intense heat, how ever, the inner surface of the oil film will be vigorously affected, and, in the absence of the air necessary for burning, three things may happen:
 Case 1. The compounds may vo- latize with decomposition.
 Case 2. The compounds may de compose with the formation of free carbon and hydrogen.
 Case 3. The compounds may de- compose with the formation of other hydrocarbon compounds of different nature.
 "The products formed in case 1 give no trouble, as being gaseous, they are carried out with the ex- haust, whether burned or not. Of the products formed under case ?, the Hydrogen would pass out of the ex- haust, whether burned or not The carbon may be blown out with the gases, or may remain in the cylinder. or not 1t remained in the cylinder would depend greatly on the condition of the oil film on the cylin- der walls. Some oils from a thick, viscous gummy deposit, which retains the carbon formed on its surface and prevents it from being blown out the exhaust. This gummy deposit gradually gets thicker and harder, eventually forming the hard carbon deposit so well kpown in cyl | finders.
 This gummy deposit is due to the action of the compounds mentioned | n case 3. The free carbon liberated | n case 2 is light and fluffy, and of it. self would not form the hard deposit | Where the compounds break up into l new compounds, however, some of he new compounds are volatile, while others are heavier and more viscous han the original compound. Con inued action of the kind mentioned n case will, therefore result in the gradual thickening of the finn, and he retention and absorption by the i'm of the carbon that it liberated will increase this effect until, finally, | hard, brittle deposit results.
 Tn the absence of any gummy de ,osit of this kind to cement the free .arbon together, the latter will gen rally be blown out through the ex- laust The oil that will give the best esults, then, is not necessarily the me that will form the least carbon. ut the one that will form the least arbon in the cylinders.
 "Oils made from asphale-base rudes have shown themselves to be much better adapted to motor cylin- ers, as far as their carbon-forming ,roclivities are concerned, than are he paraffine-base Pennsylvania oils" NEW HOIST PLANT