OF ARTS AND SCIENCES. 



97 



was probably too short, as I have found that tui at common temper- 

 atures yields the insoluble oxide in a solution of saltpetre. 



" Table XXVII. — Experiments toith Tinned Copper Pipe* — Two 

 days' exposure. lOOcc. condensed to 5cc, 



" Upon the authority of Dr. Hayes t I have ventured to speak of the 

 safe use of tinned copper pipes, notwithstanding the fact of the slow 

 erosion. 



" Iron service-pipes, such as are employed for the circulation of hot 

 water and steam, for warming purposes, have been proposed, and are in 

 use. I am informed that some persons who laid them down a few 

 months since for the distribution of Cochituate water have decided to 

 replace them with lead, on account of the rust, which unfits the water 

 for washing. , 



" Iron pipes tinned within and without have been submitted to me. I 

 have no knowledge of the durability of the coat of tin. Should it prove 

 to be lasting, this pipe will have the double advantage of the strength of 

 iron and the feeble action which tin experiences. 



" A pipe consisting of gutta percha and Lidia rubber was found to 

 yield an extract to water, which gradually diminished, until the taste 

 was no longer impaired. The strength of the specimen submitted to 

 me was not sutTicient to sustain the pressure of actual service. 



" Pipes of pure gutta percha have been proposed by Dr. Webster, 

 and, from all the experiments I have been able to make, as well as 

 from the known chemical properties of the substance, I shall not be 

 surprised to find that they may be successfully introduced into wells. 

 Its susceptibility to extension when heated, if only to the temperature 

 of boiling water, precludes its use for some of the purposes of service- 

 pipes. 



" Glass pipes have been used for the transmission of water, where 

 the descent was moderate, and the head inconsiderable. Where the 

 pressure is sufficient to supply the upper rooms of houses, practice has 



* The pipe, five eiglitlis of an iricti in diameter, was washed with warm diluted 

 hydrochloric acid, then with warm diluted potas.sa, then with distilled water, and 

 then successively exposed to the different waters mentioned above. 



t Report to the Board of Consulting Physicians, Boston, 1848. 



VOL. II. 13 



