256 ANNUAL OF SCIENTIFIC DISCOVERY. 



with the oxygen, and are so rendered harmless, and the water so treated has 

 little or no tendency to produce animal or vegetable organisms. These 

 properties are so important that this filtering medium cannot fail to be 

 speedily and extensively applied, with the best possible results. 



ACTION OF WATER IN LEAD PIPES. 



An essay has been published in the Edinburgh New Philosophical Journal, 

 by Dr. Lauder Lindsay, in which he promulgates opinions totally opposed 

 to those generally entertained by chemists regarding the action of water on 

 lead pipes. It is generally taught and believed that pure soft water acts 

 rapidly on lead, and converts it into an oxide when exposed to the atmos- 

 phere. On the other hand, it is as generally taught and believed that hard 

 water, which contains neutral salts in solution, does not become impregnated 

 with lead in passing through pipes the pure water is held to be dangerous 

 to use with lead pipes, while the impure water is considered safe. It is be- 

 lieved that the neutral salts in the water prevent it acting upon the lead, 

 while the oxygen of the pure water has such an affinity for the metal that 

 it leaves its hydrogen, and acts chemically upon it. Dr. Lindsay asserts that 

 observation and experiment have led him to conclude that certain pure soft 

 waters do not act upon lead; while certain hard waters, which are regarded 

 as most protective, do act chemically upon it, and therefore it must be dan- 

 gerous to use for conveying such water for domestic purposes. He has tried 

 experiments on a large scale, and from these he has drawn his conclusions. 

 He asserts that those before him who have made investigations on a small 

 scale have been deceived as to the results, and that water containing a small 

 portion of lead will affect some members of a family, or of a community, 

 and not others, and that the rationale of this is not well understood. From 

 what he says, the only safe course to pursue m the matter is not to use such 

 pipes at all. 



ON THE REMOVAL OF GYPSUM (SULPHATE OF LIME) FROM WATERS 



USED FOR GENERATING STEAM. 



The following suggestions by Henry Wurtz, Esq., on the removal of gyp- 

 sum from waters used in steam boilers, are found in Silliman's Journal, Yol. 

 xxvi., Xo. 78: 



When we call to mind that the crystallization of the gypsum from its hot 

 solution is the principal, and usually the only cause of the formation of the 

 destructive boiler-crusts; and that, leaving out of view the injury sustained 

 by the boiler, the actual loss of heat through the non-conducting power of 

 the crust, and other causes connected with it, has been shown to amount, in 

 the case of locomotive boilers (in France), in many cases, to forty per cent. 

 of the fuel consumed, the subject may be considered worthy of further at- 

 tention ; and I shall, therefore, present some brief calculations bearing upon it. 



In a saturated solution of gypsum, then (say, in round numbers. 1 part in 

 400), each 800 Ibs. = 800 pints =- 100 gallons, will contain 2 Ibs., and each 

 1000 gallons 20 Ibs. of sulphate of lime; which is equivalent to 24 Ibs. of pure 

 carbonate of baryta, or a little over 31 Ibs. of pure carbonate of lead. But 

 water used for steam purposes, sea-water for instance, is seldom or never a 

 saturated solution of gypsum. Let us take von Bibra's analyses of the 

 waters of the Atlantic Ocean ( Liebig $ Kopp's Jahresb. fur 1850, 621), col- 



