TRANSACTIONS OF SECTION 0. 739 



by the Barrow Shipbuilding' Co. for Messrs. Stephen Speth & Co., of Antwerp, to 

 carry petroleum in bulk in competition with the steamers, and proved successful ; 

 and it is supj^ested that the example mif^ht bo advantageously followed by others. 

 Petroleum vessels cannot be used for other purpose.s, on account of their peculiar 

 arrangement and smell. A proposal to carry palm oil in a similar manner has 

 hitherto been found impracticable on account of corrosive ingredients, which 

 attack the steel in place of preserving it as petroleum does. Electric lighting is 

 resorted to to lessen the danger of fire. The petroleum industry is exjiccted to 

 increase in the future, and it is hoped that the Persian and Arabian deposits of 

 oil may before long be worked. 



4. The Corrosion and Fouling of Ships and Antifouling Compositions.^ 



By M. HOLZAPFEL. 



After referring to the work published in 18G7 by Charles F. T. Young, dealing 

 with different trials made by the British and French Admiralties and others, and 

 to the paper at this year's meeting of the Institute of Naval Architects by Pro- 

 fessor Lewes, the author states that to obtain a successful antifouling composition 

 the action of copper and yellow metal should be imitated as closely as possible. 



In the times of the wooden sailing-vessels copper or yellow-metal sheathino- 

 was employed with very good results, and it still is so employed, lasting under 

 ordinary circumstances for three or four years, and keeping vessels clean for that 

 period. "When iron vessels were first introduced, sheathing with yellow metal, 

 zinc plates, and other metallic compounds was tried, but all failed. Many com- 

 positions were then brought into the market, but when practically tested they 

 were found to be inadequate, lasting barely six months. 



What the Government and private shipowners then aimed at was a composition 

 to last as long as copper sheathing on wooden vessels. The building of dry docks, 

 however, at all the important ports in the world, and the rapidity with which 

 vessels are now cleaned and painted, have made it unnecessary for a composition 

 to last for such a period, particularly as it is now always considered advisable to 

 dock vessels every twelve months. 



A composition which will keep a vessel clean for twelve months in ordinary 

 trades is at present likely to meet with the best success. It must, however, comply 

 with the following conditions: — 



1st. It must absolutely protect the ship against rust. 



2ndly. It must have a very smooth surface, so as to reduce surface friction to 

 a minimum. 



3rdly. It must be quick-drying. 



As to antifouling properties, there are two methods by which they are supposed 

 to be obtained : — 



1st, exfoliation, i.e., the separating of small particles of the composition from 

 the main body, by which any animal or vegetable growth which may have attached 

 itself is caused to drop off the bottom of the vessel; and, 2ndly, poisoning, by which 

 the fouling matter is supposed to be killed either before attaching itself or after. 



Some lean to the former principle, others to the latter. Mr. Young attributes 

 the antifouling properties of copper and zinc sheathing to exfoliation only, and 

 Professor Lewes, without saying so distincth', leans strongly in that direction. 

 I'oth, in the authors opinion, are wrong; for it is from the fatt that copper and 

 villow metal only poison iv/ini they exfoliate that they become antifouling, and it 

 is only metals and compositions which in exfoliating produce poisons that are 

 effective antiCoulers. 



After adducing several facts in support of his theory at length, and quoting 

 the poisons mo.stly employed by antifouling composition manufacturers of the 

 present day, he concludes by saying that any improvements in the immediate 

 future in composition can only be eft'ected by a perfect adjustment of the various 



' Printed in rxtrnso in the Sliippiny and Mercantile Gazette, September 17, 1889, 

 and the Steamship, October 1, 1889. 



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