28 Sketch of the Improvements in Science [Jan. 



advantages attending the use of magnesia and of acids in certain 

 cases of calculous complaints. 



17. Sir Everard Home's theory, that fat is formed in the lower 

 intestines, and that this formation evolves excrementitious matter, is 

 ingenious, and his paper contains some curious facts ; but the 

 hypothesis is too imperfectly supported by proofs to be likely to gain 

 credit. 



IX. Mineralogy. 



This department of science is divided into two branches; namely, 

 geosnosy and orycto^nosy : the first of wliich, owing chiefly to the 

 spirit excited by the Geological Society, has been for some years 

 cultivated in this country with much zeal and success. 



I. Geognosy, 



One of the most interesting additions to this branch of science 

 whicli has been laid before the British public for some years, is to 

 be found in Vcfti Buch's Travels in Norway, an English translation 

 of which was published during the course of last summer. In- 

 tending, as soon as possible, to lay an analysis of this book before 

 my readers, I shall not enter into any details here. The transition 

 rocks round Christiana constitute Von Buch's most important dis- 

 covery. Here he found transition granite, zircon syenite, and a 

 beautiful rock, to which he gave the name of diallage rock. The 

 greatest part of Norway is primitive, and consists of gneiss. 



I found, by traversing a considerable portion of Sweden, that 

 the gneiss extends over the greatest part of Scandinavia. The 

 floetz formations occur at the southern extremity of Sweden, 

 beginning at Helsingburg, and extending eastwards along the sea 

 coast. Several spots occur likewise in West Gothland and Dale- 

 carlia, which I considered, from the rocks composing them, to be 

 floetz rocks : but there can be no doubt that they are similar to 

 several described in Norway by Von Buch, and which he consi- 

 dered as transition. Pie founded his opinion upon the orthoceratites 

 which exist abundantly in the lime-stone ; and this species of petri- 

 faction, in his opinion, characterizes transition lime-stone; but I 

 suspect strongly that this conclusion has been drawn upon too slight 

 grounds. In the first place, nothing can be better characterized 

 than the transition lime-stone of Plymouth; yet I have never heard 

 of any person having observed an orthoceratite in that rock. In 

 the second place, I have been informed by Mr. Greenough that 

 this petrifaction occurs in Ireland in rocks decidedly belonging to 

 the floetz formation ; and Llnvydd says that they occur in Oxford- 

 shire, Northamptonshire, and Gloucestershire, where I never heard 

 that any transition rocks had been observed. These facts induce 

 me to doubt whether the occurrence of an orthoceratite in a rock 

 be a sufiicient reason for inducing us to consider it as transition. 

 The sand-stone and lime-stone wliich exist in the rocks alUided to in 

 Sweden differ very much from any transition rocks that I have ever 



