PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 551 



had exhibited to them specimens of pipe purporting to be of block tin, 

 which were in reality an alloy of tin and lead, having all the poisonous de- 

 fects of lead, without its mechanical or economical advantages. Pipe 

 which they have since seen seems not to be so alloyed. It cannot, how- 

 ever, be manufactured in large lengths. It is worked with difficulty, and 

 requires special skill in the workman. In cost, it would be at least four 

 times that of the simple lead pipe for the same work, and though cot gene- 

 rally acted upon bj' the water passing through it, it is yet speedily acted 

 upon by external agents which destroy it sooner than they destroy iron, 

 and much sooner than lead. These defects may be due to impurities in the 

 tin, and this kind of pipe may have special uses for which it is admirably 

 adapted, but for ordinary plumbing it is too expensive and does not 

 possess any great compensating advantages. 



4th. Tin-lined lead pipe combines the advantages of lead pipe, in the ease 

 with which it is made and worked, with the advantages of tin pipe in 

 not poisoning the water which flows through it. There is ua more difS- 

 culty in employing this kind of pipe than in using lead pipe, as any ordi- 

 nary plumber can bend, join and solder it with ease. It is manufactured 

 in as long lengths as lead pipe, and does not require a special solder or 

 special skill which may not be readily obtainable when repairs are needed. 

 The lead covering protects the tin from corrosive agents on the outside, 

 while the tin lining protects thes^ater from the poisonous effects of lead. 



• In conclusion, your committee report that for all cases where iron or lead 

 can be used, these are the cheapest and best materials; and that where 

 lead alone would be dangerous to health, the tin-lined lead pipe exhibited 

 to them seems to be the neatest and simplest, and most practicable device 

 for combining the useful mechanical qualities of lead with the qualities of 

 tin which preserve the water, conveyed through such pipes, pure and 

 healthy. 



All which is respectfully submitted. 



BENJAMIN GARVEY. 

 RODMAN B. DAWSON. 



• Mr. Garvey. — The first pipe which was submitted to us I had analyzed, 

 when it was found to be alloyed with lead. As far as my experience goes 

 I find that the pure tin pipe could not be worked with any degree of dex- 

 terity, and I also find that the solder for it could not be had for less than 

 $2 a pound. 



The Chairman read the following interesting summary of scientific news: 



Vanadium. 



This metal, now used in making ink, is found in small quantity in Eng- 

 lish pig iron, according to the report of Mr. Riley to the London Chemical 

 Society. It is also in the French mineral bauxite, and in a variety of iron 

 ochre. A minute portion of Vanadic acid or Vanadate of Ammonia, added 

 to a solution of nut galls, produces an intensely black ink, indelible by the 

 ordinai-y substances which remove the color of common writing ink. 



Nickel. 



Nickel ore has been discovered in large quantities in the Ramapo moun- 

 tains, in Bergen county, New Jersey, which it is said can be profitably 

 worked. 



