486 C. E. Munroe — Artificial Hematite Crystals. 



phur dioxide on the outside, for the inside of the pipes was not 

 pitted. When the pipes were removed they were found 

 incrusted on their interior surfaces with finely developed 

 and brilliant crystals of hematite, which had evidently been 

 formed by the action of the hydrochloric acid on the iron, 

 producing iron chloride, and the subsequent conversion of this 

 compound to the oxide by the air passed through the pipes. 

 These crystals were attached to the surfaces of the pipes by 

 their edges and many of them were grouped in rosettes like the 

 famous iron roses of the Alps. A noticeable fact in connection 

 with their occurrence was that the size of the crystals varied with 

 the size of the pipe in which they were produced. A six-inch 

 pipe, for instance, furnished crystals whose longest diameter 

 was about one centimeter, while a twenty-inch pipe yielded 

 crystals whose longest diameter was slightly over three 

 centimeters. 



The George Washington University, Washington, D. C. 



