The quality of water in relation to the arts and to medicine has
been very fully considered by M. E. Chevreul in his " Chemical Re-
searches on Dyeing," the thirteenth and fourteenth memoirs of which
have just been laid before the French Academy of Sciences. Although
the employment of distilled water in dyeing has been found to possess
many advantages over well-water and river-water, such as that of the
Seine (e. g., the first with salts of copper giving an azure tint, which
the other will not), yet it is found that, when woollen stuff is passed
through steam, the sulphur that is contained in the wool will form with
the salts of copper the reddest color that would have succeeded to the
azure-tinted whiteness of the wool. In accordance with the results of
many of the researches of the present day, M. Chevreul says that hw
experiments prove the grave inconveniencet of the " absolute " in our
judgments. In regard to medicinal waters, he considers that we have
Deen indebted to empiricism for our knowledge of the diverse actions
of sulphurous, femigmous, and alkaline waters in the animal economy.
He exemplifies the necessity of accurate analyses by pointing out the
errors which have ensued in the preparation of artificial mineral waters.
For instance, it has only lately been discovered that some mineral
waters contain arsenic. How, then, can'a water be prepared without
fully comprehending the effect which this iuCTcdient nas upon the hu-
man system, one which almost certainly would be lost in the imitation.
