262 A GENERAL FORMULA FOR THE 



curacy, than the mode of determining it by obtaining insulated 

 the compound salts. Nothing is more difficult than to effect 

 the entire separation of salts by crystallization, aided even by 

 the usual methods of the action of alcohol, either as a solvent 

 or a precipitant, or by the action of water as a solvent at dif- 

 ferent temperatures ; in many cases it cannot be completely 

 attained, and the analysis must be deficient in accuracy. No 

 such difficulty is attached to the other method. The princi- 

 ples being discovered, and their quantities estimated in gene- 

 ral from their precipitation in insoluble compounds, their en- 

 tire separation is easily effected. Nothing is easier, for ex- 

 ample, than to estimate the total quantity of sulphuric acid by 

 precipitation by barytes, or of lime by precipitation by oxalic 

 acid. And this method has one peculiar advantage with re- 

 gard to accuracy, that if any error is committed in the estima- 

 tion of any of the principles, it is discovered in the subsequent 

 step of inferring the binary combinations, since, if all the ele- 

 ments do not bear that due proportion to each other which is 

 necessary to produce the state of neutralization, the excess or 

 deficiency becomes apparent, and of course the error is detec- 

 ted. The indirect method, then, has every advantage over the 

 other, both in accuracy and facility of execution. 



Another advantage is derived from these views, if they are 

 just, that of precluding the discussion of questions which other- 

 wise fall to be considered, and which must often be of difficult 

 determination, if they are even capable of being determined. 

 From the state of combination being liable to be influenced by 

 evaporation, or any other analytic operation by which the salts 

 existing in a mineral water are attempted to be procured, dis- 

 cordant results will often be obtained, according to the me- 

 thods employed ; the proportions at least will be different, and 

 sometimes even products will be found by one method which 



are 



