1020] RURAL ENGINEERING. 283 



Antiseptic treatiiiGiit of timber, E. E. King {Cornell Civ. Engin., 28 {1920] 

 Ho. 6, pp. 2.'i~)-253, Jigs. 6). — Different processes for tlie preservative treutuieni 

 of timber tire briefly reviewed. 



liOlation between viscosity and penetrance of creosote into wood, E. 



BATiiMAN {Chcm. and Metall. Engin., 22 {1920), No. S, pp. S59, 360, figs. 2).— 

 A mathematical analysis of available data on the subject is given, from which 

 it is concluded that " a very definite relation exists between the viscosity of 

 the oil and the depth of penetration, and that this relation is amenable to 

 mathematical treatment. 



•• A cliange in tempeiature of the oil has no other effect than that of changing 

 the viscosity. The presence of free carbon in tar-creosote solutions has ap- 

 pai-ently no other effect than would be expected from the increased viscosity. 

 The following equatiOHS hold for longleaf pine and noble fir when tlie time of 

 treatment is two hours and the pressure 75 lbs. per square inch: 



Longitudinal penetration yx=k 

 Tangential penetration yVx^=k, 

 Radial penetration yx^=kz 



where x Is the penetration, y the absolute viscosity, /.-, /r^, and fc» constants. 

 When the pressure and time of treatment are changed the power of x and the 

 value of k are changed. Sufficient data are not available to work out the effect 

 of changes in time and pressure. The measurement of the viscosity of oils in- 

 tended for treatment is perhaps the most important measurement as far as pene- 

 trance is concerned. 



An investigation of the protective values of structural steel paints, J. S. 

 CoYE {loioa Engin. Expt. Sta. Bui. 54 {1919), pp. 68, figs. 23).— Laboratory and 

 field studies of the paints in common use for painting highway structures to 

 determine their suitability for the purpose are reported. 



It was fouad that gypsimi and whiting are harmful when present to a much 

 greater extent than 5 per cent of the pigment. In every case where these mate- 

 rials were present to a considerable extent the paint failed to protect and rusting 

 usually began underneath the film. It is conclnded that it is not safe to use carbon 

 and graphite paints for the first coat on steel. Coal-tar paints are worthless for 

 structural steel exposed to the atmosphere under ordinary conditions. Asphaltic 

 base paints as a class should not be specified as a general structural-steel coating, 

 although those which have Arithstood a good service test may be specified indi- 

 vidually. 



Red lead, sublimed blue lead, sublimed lead sulphate, and zinc and lead whites 

 are very effective for first coats and produce good surfaces for repainting. Fre- 

 quent repainting is necessary when they are used for field coats. Red lead, 

 sublimed blue lead, sublimed lead sulphate, zinc lead white, white lead, or leaded 

 zinc pigments are always safe pigments for a shop-coat paint. 



Pure iron oxid paints may be safely used for a shop coat, but should preferably 

 be mixed with about 10 per cent zinc or lead chromate. Iron oxid paints con- 

 taining gypsum or whiting in any considerable extent ai"e not serviceable for 

 either shop or field coats on structural steel. 



There are certain carbon paints on the market which produce such a strong, 

 elastic, and impermeable film that they may be used for both shop or field coats 

 for structural steel, provided the painting is done in a thoroughly good, work- 

 manlike manner. Gra^hite or carbon paints, the pigment of which contains 20 

 per cent of basic lead chromate, zinc chromate, lead oxid, or sublimed lead sul- 

 phate, are good shop-coat paints, and also prove very serviceable for field coats. 

 There is some indication that china wood oil should be excluded as a vehicle for 



