Obfervations on Blue Colours. gt 
In order to examine whence this colouring matter 
proceeded, the following experiments were made : 
ift. Some pure Soda Phofphorata was diffolved, 
to which was added a portion of the aluminous and 
martial folution. A dirty white coagulum was 
formed, which, by adding more of the precipitating 
_ liquor, was rediffolved entirely, 
2d. ‘To fome of the fame folution of Soda Phof- 
phorata was added a folution of Martial Vitriol: a 
fimilar coloured coagulum appeared, of which, upon 
furcharging it with the latter folution, the greateft 
part was rediffolved, and the remainder continued 
unchanged in colour. 
gd. With Sal Soda diffolved in water, the alumi- 
nous and martial folution precipitated a dirty white 
colour, which being overcharged with the precipita- 
ting liquor, part was rediffolved; but what remained 
was not altered in colour. | 
4th. Some of the fame folution of Sal Soda was 
precipitated with a folution of vitriolated iron: a very 
large quantity of brown precipitate was produced, 
which being overcharged with the folution of iron, 
effervefced much, and the precipitate was rediffolved. 
_ This experiment was fome time afterwards made 
with another folution of Sal Soda, and the folution 
of vitriolated iron: when a fimilar coloured preci- 
pitate was produced, but being overcharged with the 
latter, only part of the precipitate was rediffolved, 
but there was no alteration of colour. | 
M 2 5th. The 
