206 On the Connexion which exists lelween 
phates; and I shall admit with M. Berthier, that 
100-00 lead, 
The phosphate of lead is composed of 7°29 oxygen. 
; ; 31°14 acid. 
According to this, we find by calculation the following 
proportions : 
100:00 copper. 
Phosphate of copper ....4 24°57 oxygen. 
104°95 acid. 
100°00 zine. 
Phosphate of zinc....... 4 24°41 oxygen. 
104-97 acid. 
“0 . ’ 
Phosphate of mercury at \ es ae 
wad 4°16 oxveen. 
the minimum ....... oe a2 
17°76 acid. 
100°00 silver. 
7°60 oxygen, 
32°46 acid. 
Since (the proportions of a metallic salt and the oxi- 
dation of the metals being given) we may determine those 
of all the salts of one and the same kind, we may also (the 
proportions of acid and oxide of all the metallic salts and 
the oxidation of a single metal being given) calculate thar 
of all the rest. Thus, upon the supposition that the ana- 
lysis of the sulphate of lead which I used is exact, and 
that of the sulphate of barytes (66-5 of barytes and 33 5 
of acid) given by M. Berthier is correct also, we find that 
the new combustible substance extracted from barytes 
would take for 100 parts 10°77 of oxygen. In the same 
way, admitting the analysis of the muriate of soda which 
was communicated to me by M. d’Arcet, viz. 50°73 of al- 
kali and 49°27 of acid, we should find that the new com- 
bustible substance extracted from soda takes 40°21 of oxy- 
en: about four times more than the foregoing. 
We know that lead, silver, and mercury ut the minimum 
of oxidation form insoluble salts, with a very great num - 
ber of acids. These metals are precisely those which form 
neutral salts, or nearly s0, take Jess oxygen, and conse- 
quently less acid. We can easily conceive, thereture, how 
all the salts in which the oxide is at the minimum of oxi- 
dation, have more tendency to insolubility than those 
in which the oxide is at the maximum. It is a conse- 
quence of this general law, that when there is plenty of 
any insoluble principle in a compound, the latter has 
more tendency to insoiubility than when it is a souble prin- 
ciple which prevails in it. The mercury at the minimum 
forms an insoluble salt; but when it is at the maximum, it 
gives 
Phosphate of silver ..... 
