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PRZVIOUS pitper (7) described n yiinplc, coiripant A apparatus giving highly consistent data: for the rates of condensation of lomr alcohols. This allows the determination of heat transfer aoefficients using a small amount of material, requiring a short time, and measuring nll quantities precisely. In this apparatus the same tcmpertrture drop was inaintained throughout the entire length of the heating surface since the heat trmsfer surfwe wns msintnined substantially isothermal by tlie passage of eight streams of liquid through channels drilled longitudinally in : I solid bm, 1.94 inches in dismoter and 20.15 inches in effective length; adjscent streams were flowing in opposite directions to equalize the temperature of the mass of the bar and of the heat transfer surfnce. Variations in temperature normally encountered mound the circumference of a tube w r e not investigated but were probably minimized, owing to the Ittrse metal mass of tlie bar as compared to a tube.Furthermore, vapor velocity was reduced by instolling the condensing surface directly in the vapor sp:rce of the boiler itself as done in ertrlier researeti (4j. This gives the lowest possible wpar velocities and coefficients (safest from design standpoint); it also eliminates the corrections iisulrlly necessary for different velocities and pressures of vapors surrounding a tube where the vapors enter one end of an 811-nular space around the tube, m d are condensing and losing volume snd velocity from inlet to outlet.The purpose of the study was to determine data for tho design of commercial heat transfer equipment. Only two factors were to be considered as affecting bhe rate of condenFilm Coefficients for Alcohols, Esters, and Ketones Courier. Vulcan COI)PII and i u~l i l i G m w w Condrn.n Level Showing Vepor and Vent Condenserr for Distillstion Unit for Pure Alcohol (I 90" Roo0sation of organic vapors at their normal boiling pinta, which are the usual eondensing temperatures in practice: (a) the uatnre of the compound itself-i. e., its chemicsl formula; and (6) the temperature drop from the vapors to the condensing surface.In the previous work the data for iso, secondary, and tertiary alcohols did not correlate well with coefficients for straight-chain alcohols. These runs were repeated, starting with the low& tempersture drop obtainable (highest cooling water temperature) and progressively increasing the temperature drop. After the maximum temperature drop vas reached, the procedure was repeated with successively lower temperature drops The coefficients for this second seriea acre lower than tho.se obtained during tlie ascending series of temperature drops.Thus, it appeared that noncondensable gases were accumulating during the time of the run and lowering the coefficients obtained after the apparatus had heen run for 5 few hours. LVoneondenssble gases might be formed by decomposition of the alcohols boiling in contact withathe copper heating coils; for it is known that copper acts as a catalyst (or the production of hydrogen and aldehydes, partic...

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