266 ROCHESTER ACADEMY OF SCIENCE. [Jtme 21, 



have found it slow, and in many cases was unable to obtain good 

 results. 



Recently I have been experimenting with another iron solvent, 

 with the best of results in more ways than one. In testing this sol- 

 vent I found that I had a process that would prepare the slice for 

 photographic purposes, so that the very finest blades of taenite would 

 be distinctly brought out in the photograph, showing lines of taenite 

 readily that on an ordinary etched slice could scarcely be seen with a 

 very strong lens. 



This feature alone makes the process a much more desirable one 

 than any method previously used, as we are enabled to obtain a 

 photograph -showing the minutest detail as to form and structure of 

 the Widmanst'atten figures that for study of these characters is far 

 superior to the etched specimen itself, under ordinary circumstances. 

 The most important feature of the process, however, is that we have 

 no effects of acid to neutralize to keep the irons from rusting or cor- 

 roding in the future, as the solvent itself is neutral. 



In endeavoring to overcome some difficulties in experimenting 

 with another method, I had occasion to interview Prof. S. A. Latti- 

 more of the University of Rochester. In our talk he stated that 

 ammonium copper chlorid is mentioned in the books as being one of 

 the best iron solvents, and suggested that I try it. I did so, and 

 after experimenting some time with it as to strength, best manner of 

 application, etc., my hopes were more than realized. It was found 

 that the strength of the solution to obtain the desired effect was not 

 a constant one, but had to be varied according to the iron in hand. 

 It was also found that a weaker and consequently slower acting solu- 

 tion brought out the greatest detail. And much to my surprise it was 

 found that the solution coated the more nickeliferous alloys, even to 

 the minutest bands of taenite, with the chlorid of copper, leaving the 

 blades of kamacite bright and clean. 



So accurately does the opaque brick red deposit of the copper do 

 its work, that in many of the patches of plessite which to the unassisted 

 eye looks as though they >vere entirely coated with copper, a 

 lens shows the alternating layers of kamacite bright and clear not a 

 hair or more in width. 



Again, as its dissolving power upon the strongly nickeliferous 

 and least nickeliferous alloys is of a marked difference, it permits the 

 former to stand out in bold relief, thus giving prominent and 

 decided structural figures. 



