OH ciRBORAtE OF POTASH. £75 



This method is in my opinion attended with much incon- The reafoa 

 lenience, for when a tube with many perpendicular flexures ate * 

 is ufed, it muft be charged with a column of the fluid fufficient 

 to counterbalance the prelfure of the carbonic acid gas, and 

 confequently to give an elevation which expofes it to be eafily 

 broken ; and when a long horizontal pipe of glafs is employed, 

 it often happens that the chalk is exploded into the air, when 

 the pifton is opened. 



Another method appears to be more fimple and commodious Simpler method 

 than this, which is foraething like that of M. Brugnatelli, MtfcJgJ?**" 

 the Italian cheraift has not published the details of his method, 

 without which it is impoffible to be followed. 



A kilogram of chalk in powder is to be put into a bottle with 

 two or three necks, capable of containing 12 kilograms of 

 water; on this is to be poured a litre of a mixture of one and 

 a half kilogram of vitriolic acid, with nine kilograms of fpring 

 Water : the gas is expelled, and a cruft of fulphate is formed at 

 the furface of the calcareous carbonate. At the end of two 

 hours all the reft of the acid water is to be added, and the 

 bottle flopped quickly. Bubbles of the gas will be rapidly 

 difengaged, but they will by degrees be difcharged more flowly, 

 and continue to be fo moderately for twenty-four hours ; then 

 the mixture is to be ftirred with an iron rod, and the gas wilJ 

 continue to be developed for 24? hours more, with little in-* 

 terruption, ' 



I found the term of the effervefcence prolonged by the re- 

 fiftance which was oppofed to the action of the fulphuric acid 

 on the chalk by the denfity which the combination neceflarily 

 acquired ; which denfity the tendency of the fulphuric acid 

 to augment the folubiiity of the fulphate of lime, fixed to pro- 

 per limits. 



As my apparatus, with the exception of the fjrft bottle, is 

 the fame of that of M. Felletier defcribed in the fifteenth Vo- 

 lume of the Annates, I (hall not fpeak of it, but only make? 

 the following remarks: 



1. Pelletier was wrong in neglecting to ufe an intermediate 

 bottle half filled with water : which is very necelfary to fepa« 

 rate the fulphuric acid which the gas always brings over. 



2. The tubes of an inch diameter, being too difficult to be 

 bent, may be replaced by others of feven or eight lines aperture, 

 which will do equally well. ' 



T 2 3, ThfJ 





