1821.] Mr. Pltillips's Reply to Dr. Hope. 21 



the greatest product which I have obtained (quantity and strength 

 being both reckoned) weighed tk?-ce ounces and a half from 12 

 ounces of the dried sulphate of iron and 10 of the acetate oflead. The : 

 acetic acid contained about 46 per cent, of real acid ; the whole 

 product, therefore, contained 1-61 ounce of real acetic acid, at 

 the cost of 2& Id. viz. \()d. for the sulphate of iron, and lod. for 

 the acetate oflead. It is, therefore, evident, that by your pro- 

 cess the cost of an ounce of real acetic acid is lo-^d. without any 

 charge for time, fuel, waste, or vessels, either in distilling the 

 acetic acid, or preparing the acetate oflead. 



Acetate of copper appears by my experiments, detailed in the 

 last number of the Annals, to be a binacetate* of copper com- 

 posed of 



2 atoms of acetic acid 127-92 



1 atom of peroxide of copper 100*0 



3 atoms of water 33-96 



Giving 261-88 as the 



number representing it in the scale. 



I put into a retort four ounces of crystallized acetate of copper, 

 with two ounces of sulphuric acid and two ounces of water. By 

 distillation I obtained four ounces of acetic acid, containing 50 

 per cent, of real acid : the cost of the acetate of copper and'sul- 

 phuric acid amounted to l.v. 8d. ; consequently the cost of one 

 ounce of real acetic acid by this process is lOd. The quality 

 of this acid was excellent; and instead of being dearer, as you 

 suppose, than that obtained by your process, it is evidently 

 cheaper in the proportion of2 to' 3. 



Having now disposed of the consideration of the " cheaper 

 rate " at which the acetic acid is obtained by the process which 

 you adopt and defend, there are some other points of it to which 

 I wish to direct your attention. 



If acetate oflead be the salt selected for decomposition in the 

 retort to procure acetic acid, I must admit that it is better to 

 employ, as you have done, a sulphate containing water in a com- 

 bined and solid state, rather than by adding sulphuric acid ; but 

 it appears to me that you have committed a fundamental error in 

 using sulphate of iron— a salt which consists of one atom of acid 

 and one of oxide, instead of a bisalt, such as bisulphate of copper 



» Since I published this analysis, I h»ve found that Dr. Ure had previously stated 

 the result of his examination in his Dictionary of Chemist}-, He makes acetate of cop- 

 per to consist of ' 



2 atoms of acetic acid 13-26 



1 atom of peroxide of copper 10-00 



2 atoms of water 2-25 



25-51 



We differ as to weight of an atom of acetic acid, and as to the number of atoms of 



itf>r 



water 



