with the Nitric and Nitrous Acids. 265 
grammes. The white powder was treated with weak nitric 
acid, it was dissolved without effervescence with the exception of 
a black powder weighing two centigrammes, which was nothing 
but sulphuret of lead. As this sulphuret formed part of the lead 
employed in the experiment, it is evident that it must be united 
to that which had not been dissolved: consequently the four 
grammes of nitrate had dissolved 5:38 gr. of metal. As the 
sides of the matrass were opaque, I washed them with weak 
nitric acid, and added the washings to the solution of the 
white matier: notwithstanding this washing they were always 
opaque. Finally, by inspecting them more closely, I ascertained 
that the glass had been corroded ; and after evaporating the ni- 
tric solution to dryness, and taking up the residue by water, I 
obtained five centigrammes of silex. The part soluble in the 
water of the residue was nitrate of lead, which contained 47 cen- 
tigrammes of yellow oxide: the white matter was therefore 
formed of silex and hydrate of lead, retaining perhaps a little 
acid. , 
9. The solution of acid nitrate of lead which was boiled over lead, _ 
and which had been decanted in a flask, deposited, after eleven 
hours, crystals in silky needles united into stars. (They weighed 
5:95 gr. after being dried. The liquor in which they were 
formed, concentrated without the contact of the air, gave at se- 
veral times 2°71 gr. of crystals similar to the foregoing. There 
remained a mother water containing a little of this salt as well 
as of nitrite of potash; for the sulphuric acid made it emit a 
nitrous vapour, and the muriate of platina made an abundant 
precipitate in it of triple salt of potash. I separated almost the 
whole alkaline nitrite from the salt of lead by means of alcohol. 
This result strongly confirms the decomposition of the glass ob- 
served above, and seems to demonstrate that the 47 centi- 
grammes of oxide contained in the white matter had been pre- 
cipitated from the solution cf the nitrate by the alkali of the 
glass which was dissolved. 
10. To resume the facts of this experiment, and draw the 
consequence which must follow upon the hypothesis of an oxide 
more at the minimum than litharge, 5-38 gr. of lead were dis- 
solved by 4 gr. of acid nitrate of lead-which contained 2°68 gr, 
of litharge ; but as there was 0°47 gr. of the latter precipitated, it 
is evident that the lead was not oxidated but at the expense of 
2°21 gr. of litharge. Hence it follows, that by adding this 
quantity to the 5°38 gr. of lead dissolved, it is easy to ascertain. 
the composition of the oxide at the minimum, since we know 
that 2°21 gr. of litharge contain 0°158 gr. of oxygen and 2°052 
of lead. We find according to these data that 100 parts of lead 
ought to absorb 2°125 gr. of oxygen. 
11. The 
