554 . TRANSACTIONS OF THE 



atU3 for cllstniing Kme in a common gas retort, or a series of upright tuLes, 

 tlie \'apor being condGnsed in water. The English is a crucible-formed 

 retort. These retorts of all kinds are set in rows of ten or more together, 

 the space between being open for attendants. There are two ways of em- 

 ploying zinc to make brass : 1st. The zinc is put into a crucible with the 

 copper over it, and both are fused. 2nd. The zinc la fused and strips of 

 copper are introduced into the melted mass, the quantity of copper determ- 

 ining the color and properties of the brass. In making bronze powder, 

 however, the color is due rather to. the degree of heat employed, than to 

 the amount of copper. The silicate of zinc is not generally worked, unless 

 when it is associated with the carbonate. The silica must be got rid of 

 some way. The carbon from the carbonate, and the sulphur from the sul- 

 phuret, can be driven off by roasting. It may be well to call the attention 

 of members to the " plastic chloride of zinc," which may have great use in 

 some branches of the arts ; also the covering of walls with zinc paint is 

 another subject of importance. 



Professor Mason. — Ingenious men ought to devote their time to the 

 discovery of an efficient mode of covering iron pillars, ceilings, etc., with 

 this substance, which would then favor the building of y??-e-2j?-oo/ buildings, 

 which ought to be the only ones now in use in the cities of civilized men. 



Dr. Stevens drew a diagram illustrative of the bag-process. 



Professor Mason. — There has been considerable improvement made in 

 Pennsylvania, so that they now produce an article almost equal to the 



French zinc-white. Mr. , an American merchant has taken hold 



and has sold two tons in London. In speaking of the adulteration of 

 white-lead with barytes, I may say that formerly manufacturers sold their 

 own white-lead, and their hrand was known, but, when middlemen were 

 allowed to grind and use heavy spar, there was no certainty as to the 

 quality of the article. Mr. Pierce, the leading paint merchant, will buy 

 white-lead from Brandwith & Son, of London, only. Now there is no field 

 more open for improvement than the manufacture of zinc-white. The 

 French article is worth from nine to ten cents a pound, while the Pennsyl- 

 vania is worth only from four to sis. 



Dr. Gould in working silver, found the solder rough from using to much 

 heat. Probably the zinc was driven off at 700'^, while the copper and 

 silver fuse at about 1900". 



Professor Tillman. — The atomic weights of zinc and copper are so nearly 

 alike that they unite to form a homogeneous compound, which accounts for 

 brass being so uniform in composition. 



After some general conversation on water-pipes of wood, lead, iron, etc., 

 the Association adjourned. 



Subject for next meeting, " Zinc." 



