W. P. Headden — Some Phosphorescent Ccdcites. 305 



The analysis gives us no definite information relative to the 

 cause of the phosphorescence, but merely an unusual though 

 not an unknown fact relative to the composition of calcites. 

 The presence of eerie oxide in certain limestones has been 

 observed before ; and Sir William Crookes has shown the 

 presence of samaria and yttria in calcite, coral, etc. ; but this 

 is the first time, I believe, that these elements have been found 

 in such notable quantities. 



There are a few persistent peculiarities that have presented 

 themselves in the course of this work which are worthy of an 

 exhaustive investigation. The solution of the eerie oxides in 

 hydrochloric acid shows, in addition to the lines of didymia, 

 an extra line in the violet beyond the didymia line charted at 

 133-134. This line is easily observed by the aid of a small 

 direct-vision spectroscope. 



The eerie oxides obtained in this analysis have the following 

 colors ; the eerie oxide, Ce0 2 , has a pale rose-red color ; this 

 probably indicates the presence of a little didymia, though the 

 cerous hydrate was suspended in a strong solution of potassic 

 hydrate and treated with chlorine until the potassic hydrate 

 was saturated, then gently heated, filtered, washed, etc. ; and 

 again submitted to the same treatment. This was repeated 

 three times and still the eerie oxide appears to contain didymia. 



The filtrates from the precipitate of eerie hydrate were pre- 

 cipitated by the addition of oxalic acid. All of these precipi- 

 tates gave either a very light green oxide, — a greenish gray 

 might be more descriptive of this oxide, or a green with a tinge 

 of brown ; this may be praseodidymia but it is more probably 

 a mixture of didymia and samaria, which would account for 

 the brown tinge in some of the portions and the light brown 

 of two portions which no heat that I have been able to obtain 

 with the blast lamp has changed in the least. There is no 

 direct proof of the presence of lanthana ; its presence has been 

 taken as a matter of course. 



The oxalates of the yttria group yielded on ignition a yellow- 

 ish white oxide whose solution in hydrochloric acid gave an 

 excellent spectrum for erbia. In working with this group I 

 observed that there is an oxalate present which is quite insoluble 

 in cold water and in oxalic acid, but is quite soluble in hot water. 

 If the oxalates be first washed with cold water and then with 

 boiling water, the oxalate will crystallize out of the hot wash 

 water as it cools. According to the data that I find given, 

 yttria oxalate is the most soluble oxalate in this group, and of 

 it the statement is, that it is almost insoluble in pure water. 

 This oxalate gives with ammonia a white precipitate similar 

 to yttria and the other members of this group. I do not think 

 that this is due to yttria because this oxalate can be completely 



