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fome bubbles were obferv’d, as if a folution was be- 
ginning : but the liquors acquir’d no colour ■ and the 
platina, waflfd and dry’d, was found to have neither 
alter’d its appearance, or loft of its weight. The 
fire being afterwards increas’d, and the acid fpirits 
kept ftrongly boiling till they had entirely evaporated, 
no change could be obferv’d in the platina. 
2. Platina was likewife treated with nitrous mix- 
tures, ‘by proceftes fimilar to thofe, in which it had 
been expos’d to the marine fumes. After cementa- 
tion for many hours, in a red heat, with a mixture 
of three parts calcin’d vitriol, and two of melted 
nitre, the grains were recover'd not only unalter’d, 
but likewife without any deficiency in weight. 
Remark. From thefe experiments it is plain, that 
platina, equally with gold, refills the force of the 
vitriolic, marine, and nitrous acids, tho’ apply’d in 
fuch a manner, as to be capable of perfe&ly diftolving 
all other known metallic bodies. 
Experiment 4. 
Platina with aqua regia. 
1. Aqua regia, which perfedlly difTolv'd gold, 
pour’d upon platina, began to adt on it in the cold, 
and, by the afliftance of a moderate heat, llowly dif- 
l'olv’d it ; acquiring at firft a yellow colour, which 
deepen’d by degrees, as the menftruum became more 
faturated, into a dark brownifh red. A few drops of 
the faturated folution tinged a large quantity of water 
of a fine golden colour. 
2. The experiment was feveral times repeated with 
different aquas regia;, made by diftolving fea-falt and 
fal 
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