103 



Reply. 



CONNECTING AND COATING OP IRON BARS. 



therefore, a method of purifying the copper, particularly for 

 the latter purpofe ? 



Your*s refpeflfully. 

 Motley Street, J. P. Jun. 



Newcafile-upon'Tyne^ 



As the procefles for refining copper in the large way are 

 grounded upon its property of refifling oxidation more than 

 the other metals which are ufually combined with it, it may 

 be advifeable to adopt the procefs of Pelletier, with a due 

 attention to the manipulation and the proportion of manga- 

 nefe to be made ufe of. The very interefting letter of Mr. 

 Thomfon in the prefent Number, will indicate the principles 

 of operation. Mr. Halchett's excellent papers in the Philo- 

 fophical Tranfaftions, of which a correct abridgement is given 

 in our V. and VI. Volumes, fliew the mifchievousconfequences 

 of impurity in the copper for alloying the precious metals; 

 and it is but too well known, that it is difficult to be pro- 

 cured, or even to be made pure, upon a fcale of exteniive 

 magnitude, 



W.N. 



XF. 



Dcfcription of a Method of connedting Iron Bars, and coating 

 them with Lead, fo as to form folid Pillars for Light-houfes 

 on Rocks covered at High-ivater, and to defend them from 

 Corrofion. By Capt. Joseph Brodie, of the Hoyal Nqvi/,'^ 



Dcfcription of JT IG. I, Plate V. A fliews four rods of call iron, compofed 



the means of 

 coating iron 

 bars : by refer- 

 ence to the 

 drawing. 



of a number of pieces two feet long, rivetted together, in a 

 manner explained by the plate, fo as to produce the effed of 

 one bar of the thicknefs of the whole. B. A tube of call iron, 

 formed from a number of feparate pieces, each about ten 

 inches long, and which, when placed round the iron rods 

 above-mentioned, and then fcrewed together, form a mould, 

 into which the melted lead is to be poured, to coat the i^-on 



* Communicated to the Society of Arts (Memoirs, mdccciv, 

 2I>8.) who voted him the gold medal. 



rods. 



