Royal Society. 61 



Welter. By applying this correction, the velocity of sound deduced 

 from calculation corresponded very nearly with the result of actual 

 experiment. Still, however, a degree of discordance was always found 

 to take place. With a view to perfect the theory still further, Dulong 

 attempted, by reversing the process of Laplace, to deduce the co- 

 efficient by which the Newtonian formula is to be multiplied, directly 

 from experiments themselves. The object of the present paper is to 

 compare the investigation of Dulong with the experiments on the 

 velocity of sound made by Drs. Moll and Van Beck, of which an ac- 

 count has lately been published in the Phil. Trans. By applying the 

 values of the co-efficients thus obtained, the computed velocities of 

 sound came out much nearer to the observed velocities 3 and the 

 author concludes by remarking, that such differences as yet remain 

 between calculation and experiment, may, with great probability, be 

 ascribed to the errors which are unavoidable in observations of so com- 

 plicated a nature. 



"On the occurrence of Iodine and Bromine in certain mineral 

 waters of South Britain." By Charles Daubeny, M.D. F.R.S., Pro- 

 fessor of Chemistry in the University of Oxford. 



The author lays claim to being the first who announced to the 

 public the existence of bromine in the mineral springs of England : 

 a discovery similar to that which had been previously made by others 

 in many analogous situations on the continent. His reason for 

 offering the present communication to the Royal Society is, that he 

 has examined on the spot a great number of mineral springs, and en- 

 deavoured to obtain, wherever it was practicable, an approximation 

 to the proportion which iodine and bromine bear to the other ingre- 

 dients. He has also aimed at forming an estimate of their compara- 

 tive frequency and abundance in the several rock-formations ; an ob- 

 ject of considerable interest in geology, as tending to identify the 

 products of the ancient seas, in their most minute particulars, with 

 those of the present ocean. The results of his inquiries are given in 

 the form of a table, in which the springs, whose waters he examined, 

 are classified according to the geological position of the strata whence 

 they issue, and of which the several columns exhibit the total amount 

 of their saline ingredients ; the nature and proportion of each ingre- 

 dient, as ascertained by former chemists, or by the author himself; 

 and, lastly, where they contained either iodine or bromine the ratio 

 these substances bear to the quantities of water, and likewise to the 

 chlorine also present in the same spring. He finds that the propor- 

 tion of iodine to chlorine varies in every possible degree ; and that 

 even springs which are most strongly impregnated with common salt, 

 are those in which he could not detect the smallest trace of iodine. 

 The same remark, he observes, applies also to bromine ; whence he 

 considers, that although these two principles may, perhaps, never be 

 entirely absent where the muriates occur, yet their relative distribu- 

 tion is exceedingly unequal. The author conceives that these ana- 

 lyses will tend to throw some light on the connexion between the 

 chemical constitution of mineral waters and their medicinal qualities. 

 Almost the only two brine springs, properly so called, which have 



acquired 



