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Improvpments in Making White Leetd and Verdigris. S97 
pouring melted lead into a revolving cylinder, for the purpose of 
granulating it by the rotator}^ action of the machine. When the 
lead is thus granulated, it is converted into white lead by the 
ordinary processes. 
In the manufacture of verdigris, he also employs a revolving 
vessel, or a fixed vessel, in which agitators may be placed, and into 
these he puts copper in a very minute state of division. ■ Pyro- 
lignous acid or acetic acid, is then poured on the copper, so as 
to cover it only partially, and the whole is put into a state of 
agitation, so as to rub off tbe oxidated parts of the metal, and 
present fresh surfaces of it to the action of the acid. When tlie 
vessel is closed, he introduces carbonic acid gas during the ope- 
ration of the machine, and continues the process until the ver- 
digris is formed. 
9 . Account of Mr Johnson's Method (^'Consuming the Smoke 
of Steam-Engines. 
In the year 1813, the late Mr Sheffield took out a patent for 
air-conductors to his improved reverberatory furnaces, whicli, 
though it was not one of tbe objects of the inventor, had the 
effect of consuming the smoke, by converting it into flame. 
The air-conductors of Mr Sheffield were afterwards directly ap- 
plied to the consumption of smoke by Mr Wakefield of Man- 
chester ; and more recently, Mr Johnson? brewer at Salford, 
has taken out a patent for a contrivance for the same purpose, 
which is the counteipart of Mr Sheffield’s air-eonductor. Mr 
Johnson’s contrivance is represented in Plate X. Fig. 5., 
where e is the ash-hole and fire-place ; a the tpbe or leading 
part of the air-qonductor ; 5 its aperture or nrtouth ; d the flues 
leading to the chimney ; i the register ; k its handle ; gh the 
bridge of the furnace; m the iron-door for cleaning the flues ; 
f a . stop-w'ell ; n the steam-engine boiler.— See the Technical 
Repository.^ vol. i, p. 42., and the London Journal of Arts ^ vol. ii. 
p. 440. 
10. Account of Mr Sauls Fruii-Gatherer, 
This useful apparMus is represented in Plate X. Fig. 6. 
where d and b are a pair of cutters fixed to a pole, which may 
