644 THANSACTIONS OF THE 



been the first, so far as we are informed, to discover and make it 

 known. 



The phenomenon seems to have attracted attention in rrance^ 

 for some time, and was examined by M. M. Payen, Gruymard and 

 Vicat, the two latter of whom, (not suspecting the real cause of 

 the evil,) recommended as the means of preventing it, an internal 

 coating, of thin hydraulic lime mortar, applied by means of a 

 maulkin or swab : and it was for some time believed that this 

 was a complete protection. But a pretty extensive trial of this 

 material in Great Britain, seems to show that very little, if any 

 advantage results from its use : the thin and slightly adhering 

 coat of hydraulic mortar, being either removed by the action of 

 the flowing water, or when applied to pipes cast from metal readily 

 attacked by oxygen, the water finds its way through the lining to 

 the iron, in sufficient quantity to produce nodules of oxyde, which 

 increasing in extent and thickness, threw off the lime in scales. 

 For these reasons, it is injudicious to use the pipes for conveying 

 or distributing water, which are cast from iron of different quali- 

 ties mixed in the furnace, as it is by no means certain that they 

 will continue to deliver the quantity due to their dimensions; or 

 that they will not be much more rapidly destroyed by oxidation, 

 than those made from properly selected iron, of uniform quality. 



For making the best pipes, No. 2 pig iron should alone be used» 

 and this should be carefully assorted by the workmen ; and all 

 the iron used at any one casting, should be as nearly of the same 

 quality as possible : and it will be found in practice, that pipes 

 made from the hardest iron, that can be conveniently drilled or 

 cut, will be least liable to accidents while in use, as well as the 

 most durable. 



On motion of Mr. Tillman, seconded by Mr. Butler, the thanks 

 of the Club were voted to Mr. Ward, for his valuable treatise. 



Mr J. L. Mott, was requested to speak on the "iron castings." 

 He said that his long experience is iron, confirmed the remarks of 

 the chairman, as to the great difference in its qualities. He had 

 succeeded best by means of the hot-blast with some irons, and 

 best by the cold-blast with other irons. They often look equally 

 well, but he examines all the iron delivered at his furnaces very 



