472 Scientific Intelligence. [Dec. 



potash was deposited, lost in 16 hours -009 grnis. {'138 grs.) or 7*25 

 grs. per cent, and in the succeeding 16 hours -001 grm. ('015 grs.) 



3. 0-944 grms. (1453 grs.) of bi-carbonate of potash were dis- 

 solved in 1 loth ('469 troy ounce) of cold water, and evaporated to 

 dryness at a temperature of about 60", over sulphuric acid ; the loss 

 of carbonic acid and water sustained in some days was '06 grms. 

 (•926 grs.) or 636 per cent. 



4. 1-617 grms. (24*9 grs.) of bi-carbonate were dissolved in '939 

 ounces of cold water, the solution was evaporated in a vacuum over 

 caustic potash and sulphuric acid. After evaporation the residue was 

 again dissolved in '46 ounces of cold water, 14 days were occupied 

 in the process, and the salt was still moist ; the salt was therefore dis- 

 solved in water, the solution replaced by one of chloride of calcium, 

 to which some ammonia was added ; the resulting carbonate of lime 

 was filtered ; it weighed '951 grms. (14*64 grs.) and eontained 6-391 

 grs. carbonic acid. In 100 parts of the bi-carbonate this amounted 

 to 25*7 per cent. ; so that, as the carbonic acid in the bi-carbonate 

 amounts to 43*95 per cent., 1825 per cent, of carbonic acid was dis- 

 charged. There remains, therefore, some more acid than is necessary 

 to form a simple carbonate. 



5. 2*451 grms. (37'75 grs.) of bi-carbonate were dissolved in 3*75 

 ounces of cold water ; the solution was placed in a vacuum for 24 

 hours. The solution treated with chloride of calcium and ammonia 

 gave 2-211 grms. (34*049 grs.) carbonate of lime, which contained 

 14-87 grs. carbonic acid. Therefore, 39*43 per cent, of the 43*95 

 per cent, carbonic acid contained in the bi-carbonate remained in the 

 solution, and 4*52 were discharged. 



6. By repeated evaporation and solution in vacuo, in other trials, 

 as much as 10*62 per cent, of carbonic acid were given off. He 

 found that much more carbonic acid was given off when a substance 

 was placed under a receiver which could absorb the carbonic acid, 

 than when sulphuric acid alone was used. 



7- ,100 parts of bi-carbonate, when boiled at the usual atmospheric 

 pressure, gave off 11-85 per cent, of carbonic acid, while 32*10 re- 

 mained combined with the potash. 



8. 1*143 grms. (17*6 grs.) dissolved in 21^ ounces of water were 

 boiled down to 4*69 ounces ; the solution being treated with muriate 

 of lime gave 24*51 per cent, carbonate of lime. 



9. 1*056 grms. (16*17 grs.) bi-carbonate were dissolved in 3*6 

 ounces of water, and boiled in a retort, to the neck of which a tube 

 was adapted, and conveyed under mercury, whose height was some- 

 what more than an inch ; 8*95 per cent, of carbonic acid were dis- 

 charged. By increasing the pressure the quantity discharged was 

 smaller. 



It follows, from the first and second experiments, that the whole 

 of the carbonic acid and water of crystallization is so intimately 

 combined with the potash in bi-carbonate of potash, that the removal 

 of the atmospheric pressure, either by means of sulphuric acid or 

 caustic potash, has no influence in decomposing the salt, which, how- 

 ever, is the case with a solution of the salt in cold water. From the 

 fifth experiment, we learn that the removal of the atmospheric pres- 



