1819.] Scientific Intelligence. 383 



When heated, it melted and boiled, giving out water in the first 

 place ; but as the heat increased, the smell of acetic acid became 

 sensible. I kept a quantity of the salt for a few minutes in the 

 temperature of 604° ; it boiled violently for a little ; but the 

 boiling stopped, and it became solid almost at once. It was then 

 an orange-coloured powder consisting entirely of a mixture of 

 two parts protoxide of lead and one part metallic lead. 



To determine the quantity of acetic acid in this salt, I dissolved 

 50 gr. of it in distilled water, and precipitated the lead by means 

 of bicarbonate of potash, noting carefully the weight ofbicarbon- 

 ate necessary just to precipitate the whole of the oxide of lead. 

 Two different experiments indicated the quantity of acetic acid 

 in 50 gr. of the salt to be 11 gr. ; so that 100 gr. of the salt 

 contain 22 gr. of acid. The theoretical quantity, as will be seen 

 below, is 2i - 85. I ascribe the small excess indicated by my 

 trials (which amounted to 0-15 gr.) to the difficulty of determin- 

 ing the exact point of saturation. 



To determine the quantity of oxide of lead, I made three 

 experiments. 1. I weighed the carbonate of lead procured by 

 decomposing 50 gr. of the salt by bicarbonate of potash. 2. I 

 exposed 50 gr. of tWe salt to a heat of 504°, and weighed the 

 residue. 1 then (jftssolved off the oxide of lead by means of 

 acetic acid, and weighed the residual metallic lead. 3. I preci- 

 pitated 50 gr. of the salt by means of sulphuric acid, and weighed 

 the sulphate of lead, after being well washed and dried. By 

 these three methods I obtained nearly the same results. The 

 mean quantity of oxide of lead was 29-5 gr. ; so that 100 gr. at 

 the salt contain 59 gr. of protoxide of lead. The theoretic quan- 

 tity, as we shall see immediately, is 60 gr. ; but as the products 

 of each of the three experiments were collected on a filter, dried 

 in the open air, then taken off the filter, and heated to redness 

 in a platinum crucible, practical chemists will see that there 

 must have been some loss sustained. Though the experi- 

 ments were made carefuliy, yet I do not think it at all unlikely 

 thrta loss of half a grain might have been incurred, which is all 

 that is requisite to make the result of experiment agree with the 

 theoretic number. 



If we suppose this salt to be composed of an atom of acetic 

 acid and lj- atom of oxide of lead, then its composition will be 

 as follows : 



Acetic acid 21-85 



Protoxide of lend 00-00 



..trr 18-15 



100-00 



Now the quantities actually fund by the preceding aualy>is 

 were the following : 



