( 21 ) 
when the Lixivium is poured to the Solution of Vi - 
trioL> there immediately follows the Blue, which is {fill 
heighten’d by the Addition of the Spiritus Salts. 
It will not be improper to take notice, that as the 
Author orders all the Liquors, except the Spiritus Sa- 
lts , to be boiling hot when mix’d, fo it is certain the 
Colour is thereby more immediately produc’d, and looks 
more beautiful } but molt of the Experiments here men- 
tion’d were made with the Liquors cold, and the Colours 
came to their Beauty with a little walhing. In one of 
the Experiments with the Liquors cold, after the Lixi- 
vium with Blood had precipitated the Blue in the Mix- 
ture of Alum and Vitriol, by pouring in a little more 
of the Lixivium , the Blue all difappear’d, and an ugly 
muddy Colour was left } but the Addition of the Spiri- 
tus Salis foon difcharg’d that, and the Blue return’d. 
Ir) calcining the Beef and Salt of Tartar, I found the 
Matter left in the Crucible to weigh juft half of the 
whole Mixture, as in that with the Blood} but after 
the boiling it in Water, the Refiduum in the Filtre 
when dry’d, was very near a third lefs in Proportion 
than the other. From whence may be reafonably in- 
ferr’d. That the Salt of Tartar holds a larger Share of 
the Beef in the one Operation, than of the Blood in 
the other. 
Having in the former Part of this Account of the 
< PruJJian Blue prov’d, by the Experiments there men- 
tioned, that the Solution of Vitriol was the only Sub- 
ject among thofe Ingredients, that the Lixivium of 
Blood produc’d this Change of Colour in it} and having 
fince conftder’d that the Vitriol made ufe of in this Pre- 
paration, is no more than Iron dilfolv’d by a Liquor 
running from the RjyriteSy when expos’d to the Wea- 
ther, which is afterwards boil’d up and fliot into Cry- 
ftals, 
