346 . Analysis of Books. 



obvious relation to any of the electrical or other physical properties 

 of the metals themselves, when in a proper state, or to the propor- 

 tions in which they exist in combination. He proceeds to point out 

 various facts relative to the position of veins and the arrangement 

 of their contents, which he thinks are irreconcilable with any of 

 the hypotheses that have been devised to explain their origin. 



He observes that ores which conduct electricity have generally 

 some conducting substances interposed in the veins between them 

 and the surface ; a structure that appears to bear a striking analogy 

 to the ordinary galvanic combinations. He is of opinion that the 

 intensities both of heat and of electricity, and consequently of mag- 

 netism, increase in proportion to the depths of the strata under the 

 surface of the earth ; that they have an intimate connection with 

 one another ; and that the discovery of electrical currents in 

 various, and frequently opposite directions, in different, parts of the 

 same mine, may, perhaps, hereafter afford a clue to explain the de- 

 clination and variation of the magnetic needle. 



10. Sequel to a Paper on the tendency to Calculous Diseases, and oti 

 the Concretions to which such Diseases give rise. By John 

 Yelloly, M.D., F.R.S. [Read June 17, 1830.] 

 THE author, in a paper published in the last volume of the Philo- 

 sophical Transactions, gave the analysis of 328 calculi contained in 

 the collection of the Norfolk and Norwich hospital ; and has been 

 since enabled to complete the analysis of the 335 remaining speci- 

 mens which have now been divided. The results of the analysis 

 are given in a tabular form, exhibiting in the order of their occur- 

 rence from the centre the coifsecutive deposits of the different 

 materials of which the calculi are composed, according to the most 

 prominent character of each material. The most remarkable cir- 

 cumstance brought to light in the course of this investigation, is the 

 discovery of the presence of silex in one specimen composed prin- 

 cipally of oxalate of lime, and weighing about five grains. The 

 particles of silex were very minute, and were imbedded in, and dif- 

 fused through the oxalate of lirne. Three examples of a similar 

 occurrence are quoted by the author. 



The paper concludes with a few remarks on the statistical con- 

 clusions stated in his former communication. He thinks there is 

 reason to believe that the average number of calculous disorders 

 in Scotland has been much under-rated ; on the other hand, the 

 proneness to those complaints is very small in Ireland. A much 

 larger proportion of calculous cases occurs in towns than in the 

 country. 



