204 ANNUAL OP SCIENTIFIC DISCOVERY. 



the pores of charcoal by an instantaneous action. 9. The action of 

 porous bodies is not indiscriminate, but elective. Dr. R. Smith, in his 

 u Theoretical Considerations," says, " The elective nature of porous 

 bodies may be closely allied to three properties, the condensability of 

 the gases, the attraction and perhaps inclination to combine, and the 

 capacity of combination. Chemical affinity is* supposed to involve an 

 attraction which is purely chemical. We have no proof of any such 

 attraction as a separate power ; we have only a proof of the combina- 

 tion. Attraction may exist without the power of combining chemically, 

 or without, in other terms, chemical affinity, which is only known by 

 combination. The previous attraction has never yet been shown to be 

 of two kinds ; and it seems more in accordance with nature to diminish 

 than increase the number of original powers." 



THE QUALITY OF WATER IN RELATION TO THE ARTS AND 



MEDICINE. 



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 his 

 experiments prove the grave inconveniences of the " absolute " in our 

 judgments. In regard to medicinal waters, he considers that we have 

 been indebted to empiricism for our knowledge of the diverse actions 

 of sulphurous, ferruginous, 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 ingredient has upon the hu- 

 man system, one which almost certainly would be lost in the imitation. 

 To determine the true action of medicinal waters, M. Chevreul requires 

 that we should know 1, The definite matters or chemical species 

 contained in the water ; 2, The influence of the climate in which the 

 water is taken by the sick persons ; 3, The change in their habits con- 

 sequent upon their removal from home ; and, 4, The influence of their 

 respective idiosyncrasies (their physical and mental peculiarities). 



Wafer for Domestic Purposes. At a late meeting of the London 

 Chemical Society, Dr. Woods read a paper on. the character of the 

 water which should be used for drinking and domestic purposes. He 

 insisted that organic matter in water was injurious to health, and it was 

 as much the duty of a physician to prevent as to cure disease. He 

 stated that his attention was pointedly directed to this subject by the 

 case of two French ships that had been dispatched simultaneously with 

 troops from Algiers to France, and under similar circumstances except- 



