CATARACTS AND INUNDATIONS. 179 



who, in the valuable experiments on colours published by him at 

 Oxford in lG63, mentioned several re-agents capable of indicating 

 the substances dissolved in water, by the alteration produced in their 

 colours. The Academy of Sciences, from its first institution, was 

 aware of the importance of analysing mineral waters; and Duclos, 

 in 36(57, attempted the examination of the mineral waters of 

 France : the researches of this chemist may be found in the origi- 

 nal memoirs of this society. Boyle was particularly employed in 

 inquiries respecting mineral waters about the end of the seventeenth 

 century, and published a treatise on this subject in l6'85. Boulduc, 

 in the year 1729, published a method of analysing waters, which 

 is much more perfect than any which were employed before his 

 clay : it consists in evaporating these fluids at different times, and 

 separating by filtration the substances which are deposited, in pro- 

 portion as the evaporation proceeds. 



Many celebrated chemists l:ave siuce made successful experi- 

 ments on mineral waters, and almost every one made valuable dis- 

 coveries respecting the different principles contained in these fluids. 

 Bouldoc discovered natron, and determined its propertied ; Le Roi, 

 physician of Montpellier, discovered calcareous muriat ; Margraaff, 

 the muriat of magnesia; Priestly, carbonic acid; and Monnet and 

 Bergman the sulphurated or hepatic hydrogen gas. The two last 

 mentioned chemists, besides the discoveries with which they have 

 enriched the art of analysing waters, have published complete trea- 

 tises on the method of proceeding in this analysis; and have car- 

 ried this part of chemistry to a degree of perfection and accuracy 

 far exceeding that which it possessed before the time of their la- 

 bours. We are likewise in possession of particular analysis, made 

 by very goad chemists, of a great number of mineral waters, and 

 which serve to throw great light on this inquiry, which, with jus- 

 tice, is esteemed one of the most difficult ui the whole art of che- 

 mistry. The limits here prescribed do not permit us to enter at 

 large into the history of the analysis of waters, which may be found 

 in many treatises, especially one lately published by the celebrated 

 Dr. Saunders. 



Principles confalncd iji Mineral Wafer*.- -ttis but a few years? 

 since the substances capable of remaining in solution in water have 

 been accurately known. This appears to have arisen from the want 



of exact chemical methods of ascertaining the nature of these sub- 



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