1821.] Mr, R. Phillips's Analysis of Verdigris, 417 



Communication from the Rev. H. S. Trimmer respecting Mr* 

 ' ' ^ Mii .ij Herapath's Experiments, ^ ; .: ij;j vu 



f\f 1 Oil) Jitfljj . J I ,/3inHio 



SIR, Vicarage^ Heston^ Middlesex^ May ^l, \8^i. 



When Mr. Herapath had determined to publish in your valua- 

 ble work his *' Mathematical Inquiry into the Causes, Laws, and 

 principal Phaenomena of Heat, Gases, Gravitation, &c." it 

 appeared to him desirable that another paper containing the 

 result of experiments made by him, and illustrating the accuracy 

 of his views, should immediately follow ; and he had accordingly 

 made an arrangement for the appearance of this latter paper in^ 

 the number for July. / ; 



The circumstances which have rendered an alteration in this 

 plan necessary having originated with me, I consider it proper 

 to apologize to you for any inconvenience which may have 

 arisen to yourself, or for the disappointment which may be felt 

 by your readers from my withholding this paper, and placing it 

 in a different channel. 



It has now been presented to the Royal Society by Davies 

 Gilbert, Esq. MP. VPRS. &c. who received it from my hands. 

 I am, Sir, your obedient humble servant, 



H.S. Trimmer, 



)0I 'hinmi 



Article II. 

 Analysis of Verdigris, By R. PhiUips, FRSE. &c. 



Having lately had occasion to make some inquiry into the 

 different i;nethods of preparing acetic acid, my attention was of 

 course particularly directed to acetate of copper, as one of the 

 substances from which it has been often procured. Upon 

 referring to the more recent chemical authors to ascertain its 

 composition, I could not find that any analysis of it had been 

 made since that given by Proust, according to which crystallized 

 acetate of copper consists of 



Acetic acid and water , 61 



Peroxide of copper 39 



100 



From this statement, it is not possible to learn the quantity of 

 real acid contained in the salt ; 1 made, therefore, some experi- 

 ments to determine this point. Acetic acid does not form with 

 any substance a sufficiently insoluble compound to enable us to 

 determine its equivalent with precision, nor can the whole of it be 

 obtained by distillation ; I adopted as a substitute the following 

 method : One hundred grains of crystaUized acetate of copper 

 were dissolved in distilled water ; excess of hydrate of Hme was 

 added to the solution, and the mixture boiled. The oxide 6f^ 



New Series, vol, i, 2d /"' ^ ' '"i -• ■ 



