124 THE CANADIAN NATURALIST. [Vol. vii > 



but in geological order, an arrangement which has important ad- 

 vantages, and might be applied to zoological palseontology as well. 

 The concluding part of the work gives a good summary of his- 

 torical palaeontology, and there is a useful glossary and a copious 

 index. On the whole the work can be strongly commended to 

 Canadian teachers and students, and to all those who are endea- 

 vouring with such aid as they can obtain from books, to form 

 collections of fossils. d. 



The supposed Diamonds in Xanthophyllite. — Consider- 

 able interest was excited a short time back by M. Jeremejew's 

 announcement that he had discovered diamonds imbedded in a 

 rare Russian mineral known as Xanthophyllite. Wishing to 

 verify Jeremiejew's observations, Dr. Knop, of Carlsruhe, has 

 been quietly working at the subject, and has recently come to 

 to the conclusion that the so called crystals of diamond are merely 

 angular cavities, suggesting, it is true, the well-known forms in 

 which the diamond is wont to crystallize, but nevertheless desti- 

 tute of the veriest trace of diamond, or of any other mineral 

 substance. It might, however, be fairly supposed that the cavi- 

 ties, though now empty, originally contained certain crystalline 

 materials which impressed their angular form upon these hollows. 

 Some curious experiments by Knop lead, however, to an opposite 

 conclusion. He obtained thin sections of xanthophyllite, which ^ 

 when magnified 1500 diameters, appeared to be absolutely desti- 

 tute of any of these angiilar cavities ; nevertheless, after treating 

 the preparation with sulphuric acid, numerous cavities were 

 recognized exactly similar to those referred in other cases to the 

 presence of diamonds. In other experiments, fine lamellae of 

 xanthophyllite were carefully examined in all directions under 

 the microscope, and the entire absence of any crystalline impres- 

 sions then determined ; the object was then touched with a few 

 drops of concentrated sulphuric acid, and heated until white 

 fumes appeared. The preparation, when cooled, was protected 

 with a cover glass, and placed under the microscope, when it ex- 

 hibited swarms of beautiful tetrahedral cavities, sharply defined, 

 regularly formed, and arranged in parallel rows. From these and 

 other observations, the author feels justified in concluding that 

 the angular cavities in the Russian xanthophyllite have nothing 

 to do with the presence of diamonds, but owe their origin merely 

 to the corrosive action of acids. — Quarterly Journal of Science, 



