[ttrrell-graham] YUKONITE 15 



Even then, gas still continued to be slowly disengaged, but the above 

 figures are sufficient to indicate the order of the specific gravity, and 

 no further determination was made. 



In order to determine the nature of these gases, a quantity of the 

 material was heated in vacuo and the gas evolved was drawn off and 

 collected over mercury. Quantitative exactness was not aimed at, 

 but a volume of gas was obtained several times as large as that of the 

 • substance taken. On examination this proved to be almost entirely 

 carbon dioxide; the volume remaining after absorption by potash 

 solution was too small to be analysed, but it was partly, if not entirely, 

 nitrogen. This carbon dioxide does not appear to be present in the 

 mineral in the form of carbonate, since there is no perceptible effer- 

 vescence on treatment with hydrochloric acid, even after warming; 

 further, when thin fragments were examined under the microscope 

 with a high power, no cavities such as might enclose liquid carbon di- 

 oxide were observed. It would thus seem probable that the gas is 

 held in the imperfectly understood occluded state, and that its ready 

 disengagement from this condition accounts for the shattering which 

 fragments undergo when placed in water, while the extreme brittleness 

 may also be in part due to the same cause. Dr. A. S. Eve, of the McGill 

 University Physics Department kindly examined some of the material 

 for the possible presence of radioactive substances, with negative results. 



Clean material for analysis can easily be separated from the earthy 

 yellow matrix. It was found to be easily and completely soluble in 

 hydrochloric acid, with the exception that a little finely divided quartz 

 usually remains undissolved. A qualitative analysis showed the mineral 

 to be a hydrous arsenate of iron and calcium. The method used in the 

 anlaysis was as follows. 



The carefully selected material was ground up and dissolved in 

 hydrochloric acid, the solution after dilution being filtered to remove 

 the small amount of quartz which remained undissolved. The 

 solution was then treated with sodium sulphite to reduce the arsenic 

 to the arsenious state, and this was then precipitated by hydrogen 

 sulphide as As^Sg. In one case the latter was weighed directly after 

 drying at 100° C, but in two other determinations the precipitate was 

 dissolved, and after oxidising with potassium chlorate the arsenic was 

 precipitated by magnesia mixture, filtered through a Gooch crucible 

 and, after igniting, weighed as magnesium pyi'o-arsenate. The iron 

 and calcium were determined by the usual methods. 



An analysis was originally made some years ago on material taken 

 from a small specimen sent to the McGill University Mineral Depart- 

 ment by Mr. J. B. Tyrrell for identification. Two separately selected 

 samples gave the following results: — 



