Specimens of Purple Copper Ore and Copper Pyrites. 287 



cases, therefore, it would likewise seem evident that iron must 

 replace the copper, if we admit the above formula to be 

 correct, and their characters would seem likewise to 

 strengthen the opinion I have above expressed of the iso- 

 morphism of these two metals in combination with sulphur. 



This question as regards the poorer copper ores could only 

 be decided by a greater number of analyses, especially to 

 settle whether the per-centage of sulphur remains constant, 

 as is generally supposed to be the case. It has been as- 

 signed as a reason for the fluctuating per-centage of the cop- 

 per pyrites, that it results from admixture with iron pyrites. 

 If, however, we inspect them minutely, even under a glass, 

 they will generally be found to present a most perfect and 

 homogeneous mass, and apparently of the same structure 

 throughout, and they do not at all present the appearance of 

 a mixture of two different minerals, which we certainly in 

 this case would expect, were iron pyrites mechanically distri- 

 buted through the mass. 



In conclusion, although, from the imperfect nature of the 

 present communication, no definite results can be arrived at, 

 still, by drawing attention to these facts, I would express a 

 hope that it may lead other chemists to examine the matter 

 more thoroughly, and communicate their conclusions, which 

 could not fail to be acceptable both to the chemist and mi- 

 neralogist. 



On the Physical Geography of the Alps. 



Messrs Hermann and Adolph Schlagintweit, two young 

 but intelligent and accomplished Bavarian naturalists, who, 

 during long residences in the Alps, particularly in the Eastern 

 Alps (Carinthia, the Tyrol, &c.), in the years 1846-7-8, were 

 actively employed in investigating the numerous and inter- 

 esting relations illustrative of the Physical Geography of the 

 Alps, have just published a beautiful and remarkable work, 

 entitled ' Untersuchungen tJber die Physicalische Geographic 

 der Alpen in ihren beziehungen zu den phccnomenen der 

 Gletscher, zur Geologic. Meteorologie und Pflanzen Geogra- 

 phie." One volume imperial octavo, pp. 600, with maps, 



