( 6 3* ) 
Plates that they may be equally expofed to the A&ion 
of the acid Liquor, or to take out thofe that are fuffi- 
ciently cleanfed, or to put others in their room : And 
as the Liquor is more acid, or the Heat of the Vault or 
Stove is more intenfe, the Plates are fooner cleanfed * 
but it requires at lead: two Days, and fometimes a great 
deal more. This is the Method which the Germans 
employed in the Tin-works in France, conftantly made 
ufe of to prepare the Iron-plates to receive the Coat of 
Tin : But as the Author obferved, that the conftant 
Attendance upon them in the Stoves was very labori- 
ous, the Heat therein being almoft infupportable to 
thofe who are not ufed to it, he propofes fome other 
Methods which are attended with very little Trouble, 
and as fmall, if not a lefs Expence } and which upon 
Trial fucceeded full as well. Having therefore ob- 
ferved that the Iron-leaves or Plates are covered with a 
Scale or Layer, half vitrified by the Fire, on which 
Acids have none or very little Effed, he imagined that 
mftead of dijfolving the Iron in thefe acid Waters, it 
would be better to make it ruji , and thereby put it in 
a Condition to be eafier cleanfed from thefe Scales j as 
Ruft is accompanied with a fort of Fermentation and 
Rarefaction, and the Matter which rufts takes up a great- 
er Space, and raifes up whatever oppofes it. To this 
Purpofe he fteeped Iron Plates in different eager Men- 
ftruums, as in Water in which Alum, common Salt and 
Sal-armoniack were feparately diffolved $ and others of 
the fame Iron he only dipped into the fame Waters, 
and inftantly taking them out expofed theuT to the Air. 
Thefe latter were rufted by all of them, but fooner 
by that in which the Sal-armoniack was diffolved. Af- 
ter two Days, during which every Plate had been dip- 
ped 
