364 Chemical Notation of Laurent and Gerhardt. 
he same gradually acting cause will also produce occasional 
violent ruptures. E'or where the waters for a period find slow 
access to any centre of heat within the volcanic mountain 
neath its cover of rocks, the vapors will gradually accumulate til 
the pressure breaks a way through the mountain, to give exit to 
the vapors together with the compressed lavas. The: starting of 
a‘cork from a bottle of soda water and the escape of the liquid 
ell as carbonic acid gas, though a familiar incident, depends 
ona pate principle, with regard to pressure, to which even the 
lavas of a volcano must be obedient. The sudden outburst of 
lavas through fissures in the very summit of the walls about 
Kilauea may be of this character. In many cases violent earth- 
quakes should attend this mode of action. 
Arr. XXXVI.—On the Chemical Equivalents and Notation of 
_ Laurent and Gerhardt; by Cuarutes GreRHARDT 
(Translated for this shscig: from the Comptes, Rendus des Travaux de Chimie, 
1849, by T. 8. Hunt.) 
In commencing the fifth year of these Comptes Rendus, in 
which T shall have for the future, the collaboration of M. Laurent, 
I wish to recall the principal features of the notation which we 
adopt in our system, and which appears to us at the same aime 
more simple and more precise than the dualistic method. 
The numerical value of our symbols is for the metadloids, Pr 
same as in the notation of Berzelius, but for the Pa it is only 
one half.» Thus we write, H20, $02, SO, P, O,, CO, CO?, 
etc.; HCl, HBr, NH,, have likewise the same significance, as in 
the ordinary notation: but in the metallic combinations, the sym- 
bol of the metal has but one half the value assigned to it in the 
Berzelian formulas.+ 
* Except for arsenic, antimony, bismuth and uranium, which have the same value 
as in the Berzelian formulas. 
be rocolleetéit — the a of Berzelius as followed by the French 
and German 
+ It will 
chemists differs a little from that generally employed by the English 
Alina from a d bohaldaentiok of their combining volumes, was led to ad- 
‘aha oxyge d oge te to form water he pro of 1:2, and 
consequently to write the formula of the compound, In aceor 
he diy 0 the equivalents of the so-called ments, chlorine, bromine 
and iodine, and design: d the atom of hydrochloric acid, corresponding to water, 
, and thus made Hy equivalent with K, 
haye divided in the ons way the equivalents te of the metals proper, making H the 
equivalent of K, Zn, etc.—TZyranslator, 
a 
acti Si 
