240 Intelligence and Miscellaneous Articles. 



Hence from the relation 6:5:3, phosphochalcite would be iso- 

 morphous with strahlerz. 



It would appear from its general diffusion, that the arsenic acid in 

 these ores plays the same part as the phosphoric acid in those con- 

 sisting of arseniate of copper. I have found arsenic in Siberian Libe- 

 thenite, in phosphochalcite of Tagilsk and Hungary, and also in 

 Tagilite, and doubt not that other members of this group also con- 

 tain it. Even Ehlite contains a trace, which has not been mentioned 

 in the published paper. The quantity of arsenic acid appears to vary 

 in different ores ; for instance, in Siberian Libethenite a greater quan- 

 tity appears to replace phosphoric acid than in Hungarian. 



It is in any case surprising that arsenic acid, which is generally so 

 readily detected, should have remained so long undiscovered, more 

 especially in the blowpipe examination of these minerals. If these 

 be treated in the ordinary manner upon charcoal with the reducing 

 part of the flame, neither the odour nor the incrustation is at first 

 perceptible ; but by continuing the reducing action, both appear, 

 much more quickly, however, if any reducing agent be added, or if the 

 test be made in the manner described by Plattner for the detection 

 of small quantities of antimonic acid, especially of the combination 

 of this substance with oxide of copper. 



In the present case arsenic acid is most simply detected by bring- 

 ing the solution of a small quantity of the mineral into a Marsh's 

 apparatus. Arsenical mirrors may thus be prepared in sufficient 

 quantities to obtain the most decisive and indubitable results with 

 them. — Poggendorff's Annalen, vol. civ. p. 190. 



ON THE EUPHOTIDES OF MT. ROSE. BY T. STERRY HUNT. 



In the American Journal of Science for May 1858, there appeared 

 an extract from a letter of mine to Mr. J. D. Dana, describing the 

 results of some observations on the Euphotide of Mt. Rose. In this 

 note it was stated that the smaragdite of this euphotide contains 

 vanadium, and that this element had also been detected with nickel in 

 a chromiferous serpentine from Gaspe. It was not until this note 

 had been printed in the American Journal that I discovered my error, 

 which is however corrected in the list of errata of the same Number 

 of that Journal. The colouring matter of the smaragdite appears to 

 be chromic oxide, and neither in it nor in the serpentine of Gaspe 

 have I been able to verify the presence of vanadium. As the note 

 in question is copied in this Magazine for July 1858, p. 553, I take 

 this means of correcting the mistake. 



As I have before stated, the true euphotide is a mixture of smarag- 

 dite with Saussurite, the white mineral is a compact zoisite or lime- 

 alumina epidote, having a density of 3-3 — 3'4, and a hardness of 7'0. 

 In some specimens of the rock, however, cleavable grains and masses 

 of a felspar, apparently labradorite, are seen imbedded in the compact 

 Saussurite, showing the passage of the euphotide into a diallagic 

 dolerite, with which many lithologists have confounded it. In other 

 specimens the Saussurite becomes intermingled with small bladed 

 crystals of bluish-gray kyanite, exhibiting a passage into the so- 

 called disthene rock. 

 Montreal, Canada, Aug. 1, 1858. 



