abstracts: technology 75 



ZOOLOGY. — Sopra una piccola CoUezione di Onychophora da Australia. 

 Austin H. Clark. Zoologischer Anzeiger, 43, no. 7, pp. 316-319. 

 January 7, 1914. 



This paper is based upon a small collection of onychophores sent to 

 the author by Prof. R. Hamlj-n Harris, the Director of the Queensland 

 Museum, at Brisbane, Queensland. 



The species represented in the collection are Peripatoides gilesii Spen- 

 cer, P. orientalis (Fletcher) and P. oviparus (Dendy). 



In an appendix is given a complete list of all the species of onycho- 

 phores known from the Australian region (including New Britain, New 

 Guinea and the Moluccas), with the habitat of each in detail. A. H. C. 



TECHNOLOGY — Surface insulation of pipes as a means of preventing 

 damage hy electrolysis. Burton McCollum and O. S. Peters, 

 Bureau of Standards. Technologic Paper No. 15. (In press.) 

 An investigation of the subject of surface insulation of pipes as a 

 means of preventing damage to underground metallic structures by stray 

 currents from electric railways has recently been completed at the Bureau 

 of Standards. Tests were made of the various substances available for 

 the purpose of insulation of underground structures, including paints, 

 pitch and asphalt dips, pitch and paper and asphalt and felt wrappings, 

 and so forth. Test specimens were made by Hning shallow sheet iron 

 cones with the material to be tested. Before being subjected to the final 

 test each cone was filled nearly full of ten per cent salt (NaCl) solution 

 and an alternating difference of potential of 80 volts (effective) applied 

 across the coating for thirty seconds in order to be sure that it was con- 

 tinuous and without flaws. A milli-ammeter in series with the specimen 

 indicated a defective coating by a kick of the needle. The electrical 

 resistances of the perfect specimens were then approx'mately determined 

 with a Wheatstone bridge. In the case of the paints these resistances 

 were found to be of the orders of from 10^ to 10" ohms per square centi- 

 meter while for the wrappings they were much higher. 



The final test of the specimens which survived the preliminary test 

 consisted in allowing water and air alternately to come in contact with 

 the coating while a direct potential difference of either 4 or 15 volts was 

 applied across the coating. The value of the voltage applied depended 

 on the thickness and other characteristics of the coating. In some of 

 the specimens made up from each material the iron of the cone was made 

 negative and in others positive, while in the case of the paints some of 

 the specimens were subjected to the alternate action of air and water 



