392 



Royal Society. 



in future the practice of rendering liquors acid with nitric or hydro- 

 chloric acids, must be discontinued when sulphates are to be deter- 

 mined, or separated from chromates, phosphates, &c. 

 Influence of Mass on Chemical Affinity. 



The researches of the author, to illustrate the influence which 

 mass exerts on chemical affinity, are extensive ; a few of the results 

 arrived at are here given. 



The following table will clearly show the marked influence which 

 increasing volumes of nitric acid have in preventing the formation of 

 sulphate of baryta : — 



Table IV. 



Thus in this table we perceive, that as the bulk of acid increases, 

 more time is required for a precipitate to appear, although there is 

 a large excess of substance employed on the quantity necessary to 

 give an instantaneous precipitate ; and it is curious to observe how 

 wide is the space of time in each successive jar for a precipitate to 

 appear, and in jars numbers 9 and 10 no deposits were formed after 

 twenty-four hours. As the quantity of precipitate decreased rapidly 

 in each successive jar, they were gathered, and their amount deter- 

 mined with due care ; and these are the facts observed : — 



Table V. 



The results contained in this table, especially those in the last 

 column, clearlj' show the influence of mass on chemical affinity, for 

 there is no difference in any of the jars excepting the increasing bulk 



