1821.] Strontian, Limey Magnesia, Phosphoric Acid, S^c. 7 



acid, and the solution was evaporated to dryness on a sand-bath 

 at a temperature not much exceeding 100*. The dry salt was^ 

 then dissolved in distilled water. It obviously contained 3*5- 

 grs. of hme saturated with muriatic acid ; and from the result of 

 the experiment, it will immediately appear that muriate of lime 

 is a compound of 



Muriatic acid 4-625 



Lime 3*6 



Muriate of Hme 8-125 



8-75 grs. of carbonate of potash were dissolved in a separate 

 portion of distilled water, and the solution was mixed with that 

 of the muriate of lime. A double decomposition took place, 

 carbonate of lime precipitated, and the clear liquid held muriate 

 of potash in solution. A portion of this hquid was drawn off 

 and examined. It produced no change upon the colour of 

 paper stained red by cudbear.* Oxalate of ammonia occasioned 

 no precipitate in it. From these facts I consider myself entitled 

 to conclude that the whole of the carbonate of potash was 

 exactly neutralized by muriatic acid, and that the whole of the 

 lime had been precipitated in the state of a carbonate. It 

 obviously follows that the weight of an atom of lime is 3-5. This 

 is the atomic weight already assigned by Dr. Prout. My num- 

 ber is too high, and Mr. Dalton's too low. The number of 

 Wollaston and Berzelius is much nearer the truth than either 

 Dalton*s or mine, though both of them are rather too high. 



To enable the reader to judge of the accuracy of the preceding 

 conclusion, it may not be amiss to select two out of the great 

 number of experiments which 1 made with a view to determine 

 the weight of an atom of hme. 



(1.) If we suppose the atom of hme to weigh 3-625, which is 

 the atomic weight that I had pitched upon, then it is clear that 

 dry carbonate of lime must be composed of 



Carbonic acid 2*75 



Lime 3-625 



Carbonate of lime 6-375 



To verify this supposition, I dissolved 6-375 grs. of dry car- 

 bonate of lime in muriatic acid, evaporated the solution to 

 dryness, redissolved the residue in distilled water, and mixed it 

 with a solution of 8-75 grs. of carbonate of potash. After the 

 .^carbonate of hme had precipitated, a portion of the clear liquid 

 was drawn off, and some oxalate of ammonia dropped into it. 

 An abundant precipitate of oxalate of lime fell down. Hence 



♦ This is the most delicate test of alkalies that I am acquainted with. A Vfiry 

 Jnmute portion of alkali or alkaline carbonate renders it violet coloured. 



