306 INK-MAKING. 



Lastly, when saline acids, and corrosive vapours 

 are to be contained, we must then have recourse to 

 the lute called fat lute. This lute is made by form- 

 ing into a paste some dried clay, finely powdered, 

 sifted through a silken search, and moistened with 

 water; and then, by beating this paste well in a 

 mortar, with boiled linseed oil, that is, oil which 

 has been rendered dry by litharge dissolved in it, 

 this lute easily takes and retains the form given to 

 it. It is generally rolled into cylinders of a conve- 

 nient size. These are to be applied, by flattening 

 them to the joinings of the vessels, which ought to 

 be perfectly dry; because the least moisture would 

 prevent the lute from adhering. When the joinings 

 are closed with this fat lute, the whole is to be 

 covered with slips of linen, spread with lute of 

 lime and whites of eggs. These slips are to be 

 fastened with packthread. The second lute is ne- 

 cessary to keep on the fat lute, because the latter 

 remains soft, and does not become solid enough to 

 stick on alone. 



INK-MAKING, 



Inks are fluid compounds, intended to form 

 characters, or some other kinds of figures, on proper 

 grounds of paper, parchment, or such other sub- 

 stance as may be fit to receive them. 



There are two principal kinds of ink, writing 

 and printing ink. 



Writing Ink. 



When to an infusion of gall-nuts some solution 

 of" sulphate of iron (green copperas) is added, a very 



