412 Mr. T. Taylor's Observations on Urinary Calculi 



and Petit into the specific heats of metals, observes that they 

 have rendered it extremely probable that the atoms or equi- 

 valents of these elementary bodies have the same specific 

 heat; and that the usually received atomic weights of silver, 

 gold, and mercury should be halved. The table in which 

 this comparison is exhibited contains sulphur and 13 metals; 

 and with respect to it the late Dr. Turner remarks, " It will 

 be observed on inspecting the last column of the table, that 

 the product of the specific heat into the atomic weight is 

 very nearly 3 for the first eight substances. Platinum de- 

 viates visibly from the law, and bismuth and cobalt strikingly. 

 The three last metals (mercury, silver and gold) would nearly 

 coincide with the law, were their respective atomic weight 

 estimated at half the number given in the table." Waiving 

 the objections which Dr. Dalton has made to the results of 

 these experiments, it is, I think, requiring too much to ask 

 chemists to reduce the atomic weights of three metals to one 

 half, when of 3 others one deviates visibly and two strikingly 

 from the law. 



The difficulty with respect to mercury, gold, and silver 

 may, however, I think, be got over in a way which I wonder 

 did not suggest itself to Professor Johnston. If heat com- 

 bines with bodies in definite proportions, it may in some cases 

 like other elements combine in double proportions ; instead 

 therefore of halving the equivalents of these metals, let us 

 suppose that they are combined with two equivalents of heat, 

 and the revolution of atoms with which we are threatened 

 will be rescued from this source of discrepancy. 



It is an old observation that when things get to the worst 

 they will mend ; I hope therefore that two more Professors 

 may attempt to remove the difficulties of isomorphism, one by 

 multiplying the received atomic weights by 19, or any equally 

 convenient number, and the other by dividing them by the 

 same. 



LXVIII. Observations on Urinary Calculi, with a Descriptive 

 Account of the Collection in the Museum of St. BartholomeisS s 

 Hospital. By Thomas Taylor, Esq., M.R.C.S. 



To the Editors of the Philosophical Magazine and Journal, 



Gentlemen, 

 IITAVING completed the examination of the valuable col- 

 ■■--*- lection of urinary calculi, of which the specimens of 

 cystic oxide described in your April Number, p. 337, form a 

 part, may I request the insertion of the following observations, 

 should you deem them of sufficient interest to merit a place 



