^{page 419 note *} Berthelot (Ann. de Chim. et de Phys. [3], LXV., 401) made use only of baryta, his objections to potash and soda being that they always contain carbonate, and that their salts with organic acids always have a more or less alkaline reaction. The first of these objections may be got rid of by keeping the solution, freed from CO₂ in the first instance by lime water, in a number of small bottles filled full up to their tightly fitting corks. The second I have found not to apply to the bodies here in question. There is no doubt, however, that baryta solution does present considerable advantages in the greater ease with which it can be procured in a state of absolute purity; and that any carbonic acid which it may absorb is at once eliminated, thereby, however, altering the strength of the solution. My principal objection to it was its great tendency to crystallise even in solutions a long way removed from saturation.