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 
