1821.] Atomic Weight of various Metals and Acids. 143 



lost about 3-42 grs. which I consider as a little exceeding the 

 whole water in the salt. Indeed, that it loses acetic acid is 

 obvious from the smell which is emitted from it during the whole 

 time of the application of the heat. 



These unsuccessful results induced me to abandon acetate of 

 lead altogether, and to endeavour to determine the weight of 

 acetic acid in quite a different manner. 



8*75 grains of carbonate of potash obtained by exposing the 

 bicarbonate to a strong red heat were dissolved in water, and 

 saturated with acetic acid. It is obvious that this portion of 

 carbonate consisted of 



Grain*. 



Potash 6-00 



Carbonic acid 2*75 



The acetate was evaporated to dryness, exposed to a heat 

 .sufficient to fuse it, and kept for some time in a state of fusion. 

 I was in hopes that at this temperature the salt might be 

 deprived of all its water ; but the result did not answer my 

 expectation. I never was able to reduce the weight lower than 

 14*3 grs. ; so that the acetic acid present, had all the water been 

 driven off, would have weighed 8-3 grs. Now I was certain, 

 from many preliminary experiments, which, to avoid tediousness, 

 I have omitted to relate, that the weight of an atom of acetic 

 acid lay between 6 and 6*5. Acetate of potash then cannot be 

 completely freed from water without decomposing the acetic 

 acid, at least partially. When this salt is in fusion, it has a 

 blackish colour; but it becomes white, and assumes a pearly 

 lustre when it becomes solid on cooling. 



It is well known that acetate of soda is capable of bearing a 

 higher temperature without undergoing decomposition than 

 acetate of potash. I was in hopes, therefore, that I might suc- 

 ceed in determining the weight of an atom of acetic acid by 

 saturating a given weight of anhydrous carbonate of soda with 

 acetic acid, and exposing the salt to a temperature high enough 

 to drive off all the water without decomposing the salt. This 

 expectation has not been altogether disappointed. Out of at 

 least a dozen of experiments, 1 have succeeded twice in making 

 the salt perfectly dry without destroying any of the acetic acid ; 

 but in the greater number of the trials, the heat was raised so 

 high as to destroy part of the acid. The temperature at which 

 the acid begins to undergo decomposition is pretty well defined. 

 The salt may be heated to about 550° with impunity ; but at a 

 temperature which, I think, does not exceed 600°, charcoal is 

 always evolved. My experiments were made on a sand-bath, 

 and if the least inattention allowed the temperature of the sand 

 to get up to 600°, I was sure to find the salt partially decora- 

 posed. The experiments were made in four ounce phials. To 

 prevent the liquid from boiling unequally, which -endangered the 



