IRON RUST. 313 



in colour than that from experiments 10 and 11, being of a 

 dark reddish brown when scraped off with a horn spatula, 

 and powdered. The oxide weij^hed 2*14 grammes, of which 

 •184 was non-magnetic. 



Experiment No. 13.— On September 21, 1891, 736 

 grammes of bright 6-inch wire nails were placed in a 

 stoppered cyhnder of hot and freshly boiled distilled water. 

 In the course of a day or two they were coated with black 

 oxide. On May 31 the oxide was collected, but only 

 amounted to 'ISl grammes, which was feebly magnetic. 



Experiment No. 14. — 702 grammes of bright 6-inch wire 

 nails were put up with distilled water charged with carbon 

 dioxide. Gave only '211 of rust, of which but a small part 

 was magnetic. 



Experiment No. 15.— On September 22, 1891, 433-5 

 grammes of bright wire nails were placed in a stoppered 

 cyhnder, and dry ozonised oxygen from a Siemen's tube 

 passed in for 20 minutes. These nails were hardly rusted, 

 and there was insufficient rust to remove. 



Experiment No. 16. — 41 53 grammes were also put up in 

 the same way, and moist ozone passed in for about 20 

 minutes. Yielded on May 31, 1892, 1-437 grammes of 

 highly magnetic oxide. 



The absence of metallic iron was in these cases proved by 

 grinding it in an agate mortar, and in certain cases also by 

 means of iodine. 



Literature. 



Although the results of previous investigators should 

 usually have precedence, they are given at a later stage of 

 this paper mainly because most of my experiments were 

 carried out before I had time to fully look up the literature 

 of the subject. The immense number of publications and 

 amount of matter to be gone through nowadays is so over- 

 whelming that if, in all cases, the necessary searches were to 

 be made before experimenting, many questions which crop up 

 would never reach the experimental stage at all. 



In the first instance I had, from want of time, to be con- 

 tent with reference to the chemical dictionaries and other 

 standard works on Chemistry, and as they were silent upon 

 this subject, or stated that there was only one oxide of iron 

 possessing magnetic properties, I went on with the experi- 

 ments, and they were practically finished before I was able 

 to go through the journals devoted to Chemistry and allied 

 subjects. 



